Method and device for transmitting/receiving broadcast signal

ABSTRACT

A digital broadcast receiver for processing a broadcast signal, includes a tuner configured to receive the broadcast signal including Physical Layer Pipes (PLPs), wherein the PLPs carry link layer packets; and a controller coupled to the tuner, wherein the controller is configured to decode a specific PLP, acquire signaling information for header compression, wherein the signaling information for header compression includes a PLP identifier for the signaling information for header compression, profile information for representing a range of multiple protocols used to compress at least one stream, and a maximum value of a context identifier, decode another PLP to receive the at least one compressed stream based on the signaling information for header compression, and decompress the at least one compressed stream.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of U.S. patent application Ser. No.15/980,887 filed on May 16, 2018 (now U.S. Pat. No. 10,389,855 issued onAug. 20, 2019), which is a Continuation of U.S. patent application Ser.No. 14/915,816 filed on Mar. 1, 2016 (now U.S. Pat. No. 9,998,572 issuedon Jun. 12, 2018), which is the National Phase of PCT InternationalApplication No. PCT/KR2015/006506 filed on Jun. 25, 2015, which claimsthe priority benefit under 35 U.S.C. § 119(e) to U.S. ProvisionalApplication Nos. 62/054,358 filed on Sep. 23, 2014 and 62/017,798 filedon Jun. 26, 2014, all of these applications are hereby expresslyincorporated by reference into the present application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a method and apparatus fortransmitting/receiving a media signal. More specifically, the presentinvention relates to a method and apparatus for processing data aboutmedia transmitted respectively through a broadband network and abroadcast network in a broadcast system in which the broadband andbroadcast networks are combined.

Discussion of the Related Art

Transmission/reception of IP-based broadcast signals has been extendedin digital broadcast systems. Specifically, the importance of Internetprotocol (IP)-based broadcast signal transmission/reception environmentshas been emphasized in the mobile digital broadcast schemes, forexample, DVB-NGH from among European broadcast standards or ATSC-MH fromamong North American standards. In addition, it is expected that ahybrid broadcast system designed to be interoperable with a broadcastnetwork or an Internet network will be constructed in the nextgeneration broadcast system.

In the hybrid broadcast system, since a scheme of transmitting data viaan existing broadcast network and a scheme of transmitting data via abroadband network coexist, a scheme of processing the data is differentfrom that in an existing broadcast receiver.

In addition, according to expansion of an IP-based broadcast system, anemergency alert message needs to be transmitted through a broadcastnetwork. However, so far, a method for transmitting the emergency alertmessage has not been obviously defined.

Further, although many broadcast services could be provided due toexpansion of the IP-based broadcast system, a method for enabling aviewer to efficiently search for a desired broadcast service has notbeen supported.

Furthermore, although a scheme of processing data included in broadcastsignals can be expanded or changed according to expansion of thebroadcast system, how to deal with such expansion or change of the dataprocessing scheme in the broadcast system has not been provided.

SUMMARY OF THE INVENTION

A technical object to be achieved by the present invention is to solvethe aforementioned problems and provides a proper method and apparatusfor processing data when a data transmission scheme via an existingbroadcast network and a data transmission scheme via a broadband networkcoexist in a hybrid broadcast system.

Another object of the present invention is to provide a method andapparatus for efficiently transmitting an emergency alert message via abroadcast system.

Another object of the present invention is to provide a method andapparatus for enabling a viewer to efficiently search for a desiredbroadcast service.

Another object of the present invention is to provide a method forperforming an initialization procedure for data processing in a linklayer.

Another object of the present invention is to provide an efficientsignaling method when a transmission session based protocol is appliedto a broadcast system.

According to an aspect of the present invention, provided herein is abroadcast transmitter for transmitting a broadcast signal, including anInternet protocol (IP) packet generator for generating first IP packetsincluding broadcast data for a broadcast service and generating a secondIP packet including service acquisition information includinginformation necessary for fast acquisition of the broadcast service, alink layer packet generator for generating first link layer packetsincluding the first IP packets, and a broadcast signal generator forgenerating the broadcast signal including the first link layer packetsand the second IP packet.

The service acquisition information may include information identifyingan IP address of a channel for transmission of service layer signalingincluding information specifying the broadcast service.

The service acquisition information may include information identifyinga data pipe (DP) including the service layer signaling.

The second IP packet may further include a signaling information partincluding addition information used to identify a processing method ofsignaling data included in the second IP packet and the signalinginformation part may include signaling class information identifyingwhether the signaling data transmitted through the second IP packetcorresponds to the service acquisition information.

The link layer packet generator may further generate a second link layerpacket including link layer signaling data.

The second link layer packet may further include a signaling informationpart including additional information used to identify a processingmethod of the signaling data included in the second link layer packetand the signaling information part may include signaling classinformation identifying whether the signaling data transmitted throughthe second link layer packet corresponds to the service acquisitioninformation.

The link layer signaling data may include at least one of encapsulationmode information identifying an encapsulation scheme used to encapsulatethe broadcast data in a link layer, header compression mode informationidentifying a header compression scheme applied to an IP packetprocessed in the link layer, packet reconfiguration mode informationspecifying a structure of the IP packet processed in the link layer, andsignaling path configuration information identifying a path transmittingsignaling information.

According to another aspect of the present invention, provided herein isa broadcast receiver for receiving a broadcast signal, including areceiver for receiving the broadcast signal including first link layerpackets and a second Internet protocol (IP) packet, wherein the secondIP packet includes service acquisition information including informationnecessary for fast acquisition of a broadcast service, a link layerprocessing unit for acquiring first IP packets including broadcast datafor the broadcast service by decapsulating the first link layer packets,a signaling processing unit for acquiring the service acquisitioninformation by decapsulating the second IP packet, an IP packetprocessing unit for acquiring the broadcast data by decapsulating thefirst IP packets, using the service acquisition information, and aprocessor for reproducing and processing broadcast content using thebroadcast data.

The service acquisition information may include information identifyingan IP address of a channel for transmission of service layer signalingincluding information specifying the broadcast service.

The service acquisition information may include information identifyinga data pipe (DP) including the service layer signaling.

The second IP packet may further include a signaling information partincluding addition information used to identify a processing method ofsignaling data included in the second IP packet and the signalinginformation part may include signaling class information identifyingwhether the signaling data transmitted through the second IP packetcorresponds to the service acquisition information.

The link layer packet generator may further generate a second link layerpacket including link layer signaling data.

The second link layer packet may further include a signaling informationpart including additional information used to identify a processingmethod of the signaling data included in the second link layer packetand the signaling information part may include signaling classinformation identifying whether the signaling data transmitted throughthe second link layer packet corresponds to the service acquisitioninformation.

The link layer signaling data may include at least one of encapsulationmode information identifying an encapsulation scheme used to encapsulatethe broadcast data in a link layer, header compression mode informationidentifying a header compression scheme applied to an IP packetprocessed in the link layer, packet reconfiguration mode informationspecifying a structure of the IP packet processed in the link layer, andsignaling path configuration information identifying a path transmittingsignaling information.

According to the present invention, in a hybrid broadcast system, bothdata transmitted through an existing broadcast network and datatransmitted through a broadband network can be efficiently processed.

According to the present invention, an emergency alert message can beefficiently transmitted through a broadcast system.

According to the present invention, a viewer can efficiently search fora desired broadcast service.

According to the present invention, processing of a link layer that canoperate independently of change of a higher layer with respect to an IPlayer, an MPEG-2 TS layer, and other protocol layers corresponding tothe IP layer and the MPEG-2 TS layer can be performed.

According to the present invention, data can be processed in a linklayer that can independently operate without being influenced by aphysical layer through which broadcast content is to be transmitted.

According to the present invention, a layer that can be easily expandedlater can be configured through organization of functional blocksconstituting a link layer.

According to the present invention, signaling transmission can beperformed via multiple paths through a link layer, thereby acquiringefficiency of signaling transmission.

According to the present invention, bandwidth of a broadcast system anda processing time of broadcast data can be efficiently used through acontrol function of a link layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a view showing a protocol stack for a next generationbroadcasting system according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating an interface of a link layeraccording to an embodiment of the present invention.

FIG. 3 illustrates an operation in a normal mode corresponding to one ofoperation modes of a link layer according to an embodiment of thepresent invention.

FIG. 4 illustrates an operation in a transparent mode corresponding toone of operation modes of a link layer according to an embodiment of thepresent invention.

FIG. 5 illustrates a configuration of a link layer at a transmitteraccording to an embodiment of the present invention (normal mode).

FIG. 6 illustrates a configuration of a link layer at a receiveraccording to an embodiment of the present invention (normal mode).

FIG. 7 is a diagram illustrating definition according to link layerorganization type according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating processing of a broadcast signal when alogical data path includes only a normal data pipe according to anembodiment of the present invention.

FIG. 9 is a diagram illustrating processing of a broadcast signal when alogical data path includes a normal data pipe and a base data pipeaccording to an embodiment of the present invention.

FIG. 10 is a diagram illustrating processing of a broadcast signal whena logical data path includes a normal data pipe and a dedicated channelaccording to an embodiment of the present invention.

FIG. 11 is a diagram illustrating processing of a broadcast signal whena logical data path includes a normal data pipe, a base data pipe, and adedicated channel according to an embodiment of the present invention.

FIG. 12 is a diagram illustrating a detailed processing operation of asignal and/or data in a link layer of a receiver when a logical datapath includes a normal data pipe, a base data pipe, and a dedicatedchannel according to an embodiment of the present invention.

FIG. 13 is a diagram illustrating syntax of a fast information channel(FIC) according to an embodiment of the present.

FIG. 14 is a diagram illustrating syntax of an emergency alert table(EAT) according to an embodiment of the present invention.

FIG. 15 is a diagram illustrating a packet transmitted to a data pipeaccording to an embodiment of the present invention.

FIG. 16 is a diagram illustrating a detailed processing operation of asignal and/or data in each protocol stack of a transmitter when alogical data path of a physical layer includes a dedicated channel, abase DP, and a normal data DP, according to another embodiment of thepresent invention.

FIG. 17 is a diagram illustrating a detailed processing operation of asignal and/or data on each protocol stack of a receiver when a logicaldata path of a physical layer includes a dedicated channel, a base DP,and a normal data DP, according to another embodiment of the presentinvention.

FIG. 18 is a diagram illustrating a syntax of an FIC according toanother embodiment of the present invention.

FIG. 19 is a diagram illustrating signaling_Information_Part( )according to an embodiment of the present invention.

FIG. 20 is a diagram illustrating a procedure for controlling anoperation mode of a transmitter and/or a receiver in a link layeraccording to an embodiment of the present invention.

FIG. 21 is a diagram illustrating an operation in a link layer accordingto a value of a flag and a type of a packet transmitted to a physicallayer according to an embodiment of the present invention.

FIG. 22 is a diagram illustrating a descriptor for signaling a modecontrol parameter according to an embodiment of the present invention.

FIG. 23 is a diagram illustrating an operation of a transmitter forcontrolling an operation mode according to an embodiment of the presentinvention.

FIG. 24 is a diagram illustrating an operation of a receiver forprocessing a broadcast signal according to an operation mode accordingto an embodiment of the present invention.

FIG. 25 is a diagram illustrating information for identifying anencapsulation mode according to an embodiment of the present invention.

FIG. 26 is a diagram illustrating information for identifying a headercompression mode according to an embodiment of the present invention.

FIG. 27 is a diagram illustrating information for identifying a packetreconfiguration mode according to an embodiment of the presentinvention.

FIG. 28 is a diagram illustrating a context transmission mode accordingto an embodiment of the present invention.

FIG. 29 is a diagram illustrating initialization information when RoHCis applied by a header compression scheme according to an embodiment ofthe present invention.

FIG. 30 is a diagram illustrating information for identifying link layersignaling path configuration according to an embodiment of the presentinvention.

FIG. 31 is a diagram illustrating information about signaling pathconfiguration by a bit mapping scheme according to an embodiment of thepresent invention.

FIG. 32 is a flowchart illustrating a link layer initializationprocedure according to an embodiment of the present invention.

FIG. 33 is a flowchart illustrating a link layer initializationprocedure according to another embodiment of the present invention.

FIG. 34 is a diagram illustrating a signaling format for transmitting aninitialization parameter according to an embodiment of the presentinvention.

FIG. 35 is a diagram illustrating a signaling format for transmitting aninitialization parameter according to another embodiment of the presentinvention.

FIG. 36 is a diagram illustrating a signaling format for transmitting aninitialization parameter according to another embodiment of the presentinvention.

FIG. 37 is a diagram illustrating a receiver according to an embodimentof the present invention.

FIG. 38 is a diagram illustrating a broadcast system according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.

Although most terms of elements in this specification have been selectedfrom general ones widely used in the art taking into considerationfunctions thereof in this specification, the terms may be changeddepending on the intention or convention of those skilled in the art orthe introduction of new technology. Some terms have been arbitrarilyselected by the applicant and their meanings are explained in thefollowing description as needed. Thus, the terms used in thisspecification should be construed based on the overall content of thisspecification together with the actual meanings of the terms rather thantheir simple names or meanings.

The term “signaling” in the present invention may indicate that serviceinformation (SI) that is transmitted and received from a broadcastsystem, an Internet system, and/or a broadcast/Internet convergencesystem. The service information (SI) may include broadcast serviceinformation (e.g., ATSC-SI and/or DVB-SI) received from the existingbroadcast systems.

The term “broadcast signal” may conceptually include not only signalsand/or data received from a terrestrial broadcast, a cable broadcast, asatellite broadcast, and/or a mobile broadcast, but also signals and/ordata received from bidirectional broadcast systems such as an Internetbroadcast, a broadband broadcast, a communication broadcast, a databroadcast, and/or VOD (Video On Demand).

The term “PLP” may indicate a predetermined unit for transmitting datacontained in a physical layer. Therefore, the term “PLP” may also bereplaced with the terms ‘data unit’ or ‘data pipe’ as necessary.

A hybrid broadcast service configured to interwork with the broadcastnetwork and/or the Internet network may be used as a representativeapplication to be used in a digital television (DTV) service. The hybridbroadcast service transmits, in real time, enhancement data related tobroadcast A/V (Audio/Video) contents transmitted through the terrestrialbroadcast network over the Internet, or transmits, in real time, someparts of the broadcast A/V contents over the Internet, such that userscan experience a variety of contents.

FIG. 1 is a view showing a protocol stack for a next generationbroadcasting system according to an embodiment of the present invention.

The broadcasting system according to the present invention maycorrespond to a hybrid broadcasting system in which an Internet Protocol(IP) centric broadcast network and a broadband are coupled.

The broadcasting system according to the present invention may bedesigned to maintain compatibility with a conventional MPEG-2 basedbroadcasting system.

The broadcasting system according to the present invention maycorrespond to a hybrid broadcasting system based on coupling of an IPcentric broadcast network, a broadband network, and/or a mobilecommunication network (or a cellular network).

Referring to the figure, a physical layer may use a physical protocoladopted in a broadcasting system, such as an ATSC system and/or a DVBsystem. For example, in the physical layer according to the presentinvention, a transmitter/receiver may transmit/receive a terrestrialbroadcast signal and convert a transport frame including broadcast datainto an appropriate form.

In an encapsulation layer, an IP datagram is acquired from informationacquired from the physical layer or the acquired IP datagram isconverted into a specific frame (for example, an RS Frame, GSE-lite,GSE, or a signal frame). The frame main include a set of IP datagrams.For example, in the encapsulation layer, the transmitter include dataprocessed from the physical layer in a transport frame or the receiverextracts an MPEG-2 TS and an IP datagram from the transport frameacquired from the physical layer.

A fast information channel (FIC) includes information (for example,mapping information between a service ID and a frame) necessary toaccess a service and/or content. The FIC may be named a fast accesschannel (FAC).

The broadcasting system according to the present invention may useprotocols, such as an Internet Protocol (IP), a User Datagram Protocol(UDP), a Transmission Control Protocol (TCP), an Asynchronous LayeredCoding/Layered Coding Transport (ALC/LCT), a Rate Control Protocol/RTPControl Protocol (RCP/RTCP), a Hypertext Transfer Protocol (HTTP), and aFile Delivery over Unidirectional Transport (FLUTE). A stack betweenthese protocols may refer to the structure shown in the figure.

In the broadcasting system according to the present invention, data maybe transported in the form of an ISO based media file format (ISOBMFF).An Electrical Service Guide (ESG), Non Real Time (NRT), Audio/Video(A/V), and/or general data may be transported in the form of theISOBMFF.

Transport of data through a broadcast network may include transport of alinear content and/or transport of a non-linear content.

Transport of RTP/RTCP based A/V and data (closed caption, emergencyalert message, etc.) may correspond to transport of a linear content.

An RTP payload may be transported in the form of an RTP/AV streamincluding a Network Abstraction Layer (NAL) and/or in a formencapsulated in an ISO based media file format. Transport of the RTPpayload may correspond to transport of a linear content. Transport inthe form encapsulated in the ISO based media file format may include anMPEG DASH media segment for A/V, etc.

Transport of a FLUTE based ESG, transport of non-timed data, transportof an NRT content may correspond to transport of a non-linear content.These may be transported in an MIME type file form and/or a formencapsulated in an ISO based media file format. Transport in the formencapsulated in the ISO based media file format may include an MPEG DASHmedia segment for A/V, etc.

Transport through a broadband network may be divided into transport of acontent and transport of signaling data.

Transport of the content includes transport of a linear content (A/V anddata (closed caption, emergency alert message, etc.)), transport of anon-linear content (ESG, non-timed data, etc.), and transport of a MPEGDASH based Media segment (A/V and data).

Transport of the signaling data may be transport including a signalingtable (including an MPD of MPEG DASH) transported through a broadcastingnetwork.

In the broadcasting system according to the present invention,synchronization between linear/non-linear contents transported throughthe broadcasting network or synchronization between a contenttransported through the broadcasting network and a content transportedthrough the broadband may be supported. For example, in a case in whichone UD content is separately and simultaneously transported through thebroadcasting network and the broadband, the receiver may adjust thetimeline dependent upon a transport protocol and synchronize the contentthrough the broadcasting network and the content through the broadbandto reconfigure the contents as one UD content.

An applications layer of the broadcasting system according to thepresent invention may realize technical characteristics, such asInteractivity, Personalization, Second Screen, and automatic contentrecognition (ACR). These characteristics are important in extension fromATSC 2.0 to ATSC 3.0. For example, HTML5 may be used for acharacteristic of interactivity.

In a presentation layer of the broadcasting system according to thepresent invention, HTML and/or HTML5 may be used to identify spatial andtemporal relationships between components or interactive applications.

In the present invention, signaling includes signaling informationnecessary to support effective acquisition of a content and/or aservice. Signaling data may be expressed in a binary or XMK form. Thesignaling data may be transmitted through the terrestrial broadcastingnetwork or the broadband.

A real-time broadcast A/V content and/or data may be expressed in an ISOBase Media File Format, etc. In this case, the A/V content and/or datamay be transmitted through the terrestrial broadcasting network in realtime and may be transmitted based on IP/UDP/FLUTE in non-real time.Alternatively, the broadcast A/V content and/or data may be received byreceiving or requesting a content in a streaming mode using DynamicAdaptive Streaming over HTTP (DASH) through the Internet in real time.In the broadcasting system according to the embodiment of the presentinvention, the received broadcast A/V content and/or data may becombined to provide various enhanced services, such as an Interactiveservice and a second screen service, to a viewer.

In a hybrid-based broadcast system of a TS and an IP stream, a linklayer may be used to transmit data having a TS or IP stream type. Whenvarious types of data are to be transmitted through a physical layer,the link layer may convert the data into a format supported by thephysical layer and deliver the converted data to the physical layer. Inthis way, the various types of data may be transmitted through the samephysical layer. Here, the physical layer may correspond to a step oftransmitting data using an MIMO/MISO scheme or the like by interleaving,multiplexing, and/or modulating the data.

The link layer needs to be designed such that an influence on anoperation of the link layer is minimized even when a configuration ofthe physical layer is changed. In other words, the operation of the linklayer needs to be configured such that the operation may be compatiblewith various physical layers.

The present invention proposes a link layer capable of independentlyoperating irrespective of types of an upper layer and a lower layer. Inthis way, it is possible to support various upper layers and lowerlayers. Here, the upper layer may refer to a layer of a data stream suchas a TS stream, an IP stream, or the like. Here, the lower layer mayrefer to the physical layer. In addition, the present invention proposesa link layer having a correctable structure in which a functionsupportable by the link layer may be extended/added/deleted. Moreover,the present invention proposes a scheme of including an overheadreduction function in the link layer such that radio resources may beefficiently used.

In this figure, protocols and layers such as IP, UDP, TCP, ALC/LCT,RCP/RTCP, HTTP, FLUTE, and the like are as described above.

In this figure, a link layer t88010 may be another example of theabove-described data link (encapsulation) part. The present inventionproposes a configuration and/or an operation of the link layer t88010.The link layer t88010 proposed by the present invention may processsignaling necessary for operations of the link layer and/or the physicallayer. In addition, the link layer t88010 proposed by the presentinvention may encapsulate TS and IP packets and the like, and performoverhead reduction in this process.

The link layer t88010 proposed by the present invention may be referredto by several terms such as data link layer, encapsulation layer, layer2, and the like. According to a given embodiment, a new term may beapplied to the link layer and used.

FIG. 2 is a conceptual diagram illustrating an interface of a link layeraccording to an embodiment of the present invention.

Referring to FIG. 2, the transmitter may consider an exemplary case inwhich IP packets and/or MPEG-2 TS packets mainly used in the digitalbroadcasting are used as input signals. The transmitter may also supporta packet structure of a new protocol capable of being used in the nextgeneration broadcast system. The encapsulated data of the link layer andsignaling information may be transmitted to a physical layer. Thetransmitter may process the transmitted data (including signaling data)according to the protocol of a physical layer supported by the broadcastsystem, such that the transmitter may transmit a signal including thecorresponding data.

On the other hand, the receiver may recover data and signalinginformation received from the physical layer into other data capable ofbeing processed in a higher layer. The receiver may read a header of thepacket, and may determine whether a packet received from the physicallayer indicates signaling information (or signaling data) or recognitiondata (or content data).

The signaling information (i.e., signaling data) received from the linklayer of the transmitter may include first signaling information that isreceived from an upper layer and needs to be transmitted to an upperlayer of the receiver; second signaling information that is generatedfrom the link layer and provides information regarding data processingin the link layer of the receiver; and/or third signaling informationthat is generated from the upper layer or the link layer and istransferred to quickly detect specific data (e.g., service, content,and/or signaling data) in a physical layer.

FIG. 3 illustrates an operation in a normal mode corresponding to one ofoperation modes of a link layer according to an embodiment of thepresent invention.

The link layer proposed by the present invention may have variousoperation modes for compatibility between an upper layer and a lowerlayer. The present invention proposes a normal mode and a transparentmode of the link layer. Both the operation modes may coexist in the linklayer, and an operation mode to be used may be designated usingsignaling or a system parameter. According to a given embodiment, one ofthe two operation modes may be implemented. Different modes may beapplied according to an IP layer, a TS layer, and the like input to thelink layer. In addition, different modes may be applied for each streamof the IP layer and for each stream of the TS layer.

According to a given embodiment, a new operation mode may be added tothe link layer. The new operation mode may be added based onconfigurations of the upper layer and the lower layer. The new operationmode may include different interfaces based on the configurations of theupper layer and the lower layer. Whether to use the new operation modemay be designated using signaling or a system parameter.

In the normal mode, data may be processed through all functionssupported by the link layer, and then delivered to a physical layer.

First, each packet may be delivered to the link layer from an IP layer,an MPEG-2 TS layer, or another particular layer t89010. In other words,an IP packet may be delivered to the link layer from an IP layer.Similarly, an MPEG-2 TS packet may be delivered to the link layer fromthe MPEG-2 TS layer, and a particular packet may be delivered to thelink layer from a particular protocol layer.

Each of the delivered packets may go through or not go through anoverhead reduction process t89020, and then go through an encapsulationprocess t89030.

First, the IP packet may go through or not go through the overheadreduction process t89020, and then go through the encapsulation processt89030. Whether the overhead reduction process t89020 is performed maybe designated by signaling or a system parameter. According to a givenembodiment, the overhead reduction process t89020 may be performed ornot performed for each IP stream. An encapsulated IP packet may bedelivered to the physical layer.

Second, the MPEG-2 TS packet may go through the overhead reductionprocess t89020, and go through the encapsulation process t89030. TheMPEG-2 TS packet may not be subjected to the overhead reduction processt89020 according to a given embodiment. However, in general, a TS packethas sync bytes (0×47) and the like at the front and thus it may beefficient to eliminate such fixed overhead. The encapsulated TS packetmay be delivered to the physical layer.

Third, a packet other than the IP or TS packet may or may not go throughthe overhead reduction process t89020, and then go through theencapsulation process t89030. Whether or not the overhead reductionprocess t89020 is performed may be determined according tocharacteristics of the corresponding packet. Whether the overheadreduction process t89020 is performed may be designated by signaling ora system parameter. The encapsulated packet may be delivered to thephysical layer.

In the overhead reduction process t89020, a size of an input packet maybe reduced through an appropriate scheme. In the overhead reductionprocess t89020, particular information may be extracted from the inputpacket or generated. The particular information is information relatedto signaling, and may be transmitted through a signaling region. Thesignaling information enables a receiver to restore an original packetby restoring changes due to the overhead reduction process t89020. Thesignaling information may be delivered to a link layer signaling processt89050.

The link layer signaling process t89050 may transmit and manage thesignaling information extracted/generated in the overhead reductionprocess t89020. The physical layer may have physically/logically dividedtransmission paths for signaling, and the link layer signaling processt89050 may deliver the signaling information to the physical layeraccording to the divided transmission paths. Here, the above-describedFIC signaling process t89060, EAS signaling process t89070, or the likemay be included in the divided transmission paths. Signaling informationnot transmitted through the divided transmission paths may be deliveredto the physical layer through the encapsulation process t89030.

Signaling information managed by the link layer signaling process t89050may include signaling information delivered from the upper layer,signaling information generated in the link layer, a system parameter,and the like. Specifically, the signaling information may includesignaling information delivered from the upper layer to be subsequentlydelivered to an upper layer of the receiver, signaling informationgenerated in the link layer to be used for an operation of a link layerof the receiver, signaling information generated in the upper layer orthe link layer to be used for rapid detection in a physical layer of thereceiver, and the like.

Data going through the encapsulation process t89030 and delivered to thephysical layer may be transmitted through a data pipe (DP) t89040. Here,the DP may be a physical layer pipe (PLP). Signaling informationdelivered through the above-described divided transmission paths may bedelivered through respective transmission paths. For example, an FICsignal may be transmitted through an FIC t89080 designated in a physicalframe. In addition, an EAS signal may be transmitted through an EACt89090 designated in a physical frame. Information about presence of adedicated channel such as the FIC, the EAC, or the like may betransmitted to a preamble area of the physical layer through signaling,or signaled by scrambling a preamble using a particular scramblingsequence. According to a given embodiment, FIC signaling/EAS signalinginformation may be transmitted through a general DP area, PLS area, orpreamble rather than a designated dedicated channel.

The receiver may receive data and signaling information through thephysical layer. The receiver may restore the received data and signalinginformation into a form processable in the upper layer, and deliver therestored data and signaling information to the upper layer. This processmay be performed in the link layer of the receiver. The receiver mayverify whether a received packet is related to the signaling informationor the data by reading a header of the packet and the like. In addition,when overhead reduction is performed at a transmitter, the receiver mayrestore a packet, overhead of which has been reduced through theoverhead reduction process, to an original packet. In this process, thereceived signaling information may be used.

FIG. 4 illustrates an operation in a transparent mode corresponding toone of operation modes of a link layer according to an embodiment of thepresent invention.

In the transparent mode, data may not be subjected to functionssupported by the link layer or may be subjected to some of thefunctions, and then delivered to a physical layer. In other words, inthe transparent mode, a packet delivered to an upper layer may bedelivered to a physical layer without going through a separate overheadreduction and/or encapsulation process. Other packets may go through theoverhead reduction and/or encapsulation process as necessary. Thetransparent mode may be referred to as a bypass mode, and another termmay be applied to the transparent mode.

According to a given embodiment, some packets may be processed in thenormal mode and some packets may be processed in the transparent modebased on characteristics of the packets and a system operation.

A packet to which the transparent mode may be applied may be a packethaving a type well known to a system. When the packet may be processedin the physical layer, the transparent mode may be used. For example, awell-known TS or IP packet may go through separate overhead reductionand input formatting processes in the physical layer and thus thetransparent mode may be used in a link layer step. When the transparentmode is applied and a packet is processed through input formatting andthe like in the physical layer, an operation such as the above-describedTS header compression may be performed in the physical layer. On theother hand, when the normal mode is applied, a processed link layerpacket may be treated as a GS packet and processed in the physicallayer.

In the transparent mode, a link layer signaling module may be includedwhen signal transmission needs to be supported. As described above, thelink layer signaling module may transmit and manage signalinginformation. The signaling information may be encapsulated andtransmitted through a DP, and FIC signaling information and EASsignaling information having divided transmission paths may betransmitted through an FIC and an EAC, respectively.

In the transparent mode, whether information corresponds to signalinginformation may be displayed using a fixed IP address and port number.In this case, the signaling information may be filtered to configure alink layer packet, and then transmitted through the physical layer.

FIG. 5 illustrates a configuration of a link layer at a transmitteraccording to an embodiment of the present invention (normal mode).

The present embodiment is an embodiment presuming that an IP packet isprocessed. The link layer at the transmitter may largely include a linklayer signaling part for processing signaling information, an overheadreduction part, and/or an encapsulation part from a functionalperspective. The link layer at the transmitter may further include ascheduler t91020 for a control of the entire operation of the link layerand scheduling, input and output parts of the link layer, and/or thelike.

First, upper layer signaling information and/or system parameter t91010may be delivered to the link layer. In addition, an IP stream includingIP packets may be delivered to the link layer from an IP layer t91110.

As described above, the scheduler t91020 may determine and controloperations of several modules included in the link layer. The deliveredsignaling information and/or system parameter t91010 may be filtered orused by the scheduler t91020. Information corresponding to a part of thedelivered signaling information and/or system parameter t91010 andnecessary for a receiver may be delivered to the link layer signalingpart. In addition, information corresponding to a part of the signalinginformation and necessary for an operation of the link layer may bedelivered to an overhead reduction control block t91120 or anencapsulation control block t91180.

The link layer signaling part may collect information to be transmittedas signaling in the physical layer, and transform/configure theinformation in a form suitable for transmission. The link layersignaling part may include a signaling manager t91030, a signalingformatter t91040, and/or a buffer for channels t91050.

The signaling manager t91030 may receive signaling information deliveredfrom the scheduler t91020, signaling delivered from the overheadreduction part, and/or context information. The signaling manager t91030may determine paths for transmission of the signaling information withrespect to delivered data. The signaling information may be deliveredthrough the paths determined by the signaling manager t91030. Asdescribed in the foregoing, signaling information to be transmittedthrough divided channels such as an FIC, an EAS, and the like may bedelivered to the signaling formatter t91040, and other signalinginformation may be delivered to an encapsulation buffer t91070.

The signaling formatter t91040 may format associated signalinginformation in forms suitable for respective divided channels so thatthe signaling information may be transmitted through separately dividedchannels. As described in the foregoing, the physical layer may includephysically/logically divided separate channels. The divided channels maybe used to transmit FIC signaling information or EAS-relatedinformation. The FIC or EAS-related information may be divided by thesignaling manager t91030 and input to the signaling formatter t91040.The signaling formatter t91040 may format information such that theinformation is suitable for respective separate channels. Besides theFIC and the EAS, when the physical layer is designed to transmitparticular signaling information through separately divided channels, asignaling formatter for the particular signaling information may beadded. Through this scheme, the link layer may be compatible withvarious physical layers.

The buffer for channels t91050 may deliver signaling informationdelivered from the signaling formatter t91040 to designated dedicatedchannels t91060. The number and content of the dedicated channels t91060may vary depending on an embodiment.

As described in the foregoing, the signaling manager t91030 may deliversignaling information which is not delivered to a dedicated channel tothe encapsulation buffer t91070. The encapsulation buffer t91070 mayfunction as a buffer that receives the signaling information notdelivered to the dedicated channel.

An encapsulation for signaling information t91080 may encapsulate thesignaling information not delivered to the dedicated channel. Atransmission buffer t91090 may function as a buffer that delivers theencapsulated signaling information to a DP for signaling informationt91100. Here, the DP for signaling information t91100 may refer to theabove-described PLS area.

The overhead reduction part may allow efficient transmission byeliminating overhead of packets delivered to the link layer. It ispossible to configure overhead reduction parts, the number of which isthe same as the number of IP streams input to the link layer.

An overhead reduction buffer t91130 may receive an IP packet deliveredfrom an upper layer. The delivered IP packet may be input to theoverhead reduction part through the overhead reduction buffer t91130.

An overhead reduction control block t91120 may determine whether toperform overhead reduction on a packet stream input to the overheadreduction buffer t91130. The overhead reduction control block t91120 maydetermine whether to perform overhead reduction for each packet stream.When overhead reduction is performed on the packet stream, packets maybe delivered to an RoHC compressor t91140 and overhead reduction may beperformed. When overhead reduction is not performed on the packetstream, packets may be delivered to the encapsulation part andencapsulation may be performed without overhead reduction. Whether toperform overhead reduction on packets may be determined by signalinginformation t91010 delivered to the link layer. The signalinginformation t91010 may be delivered to the encapsulation control blockt91180 by the scheduler t91020.

The RoHC compressor t91140 may perform overhead reduction on a packetstream. The RoHC compressor t91140 may compress headers of packets.Various schemes may be used for overhead reduction. Overhead reductionmay be performed by schemes proposed in the present invention. Thepresent embodiment presumes an IP stream and thus the compressor isexpressed as the RoHC compressor. However, the term may be changedaccording to a given embodiment. In addition, an operation is notrestricted to compression of an IP stream, and overhead reduction may beperformed on all types of packets by the RoHC compressor t91140.

A packet stream configuration block t91150 may divide IP packets havingcompressed headers into information to be transmitted to a signalingregion and information to be transmitted to a packet stream. Theinformation to be transmitted to the packet stream may refer toinformation to be transmitted to a DP area. The information to betransmitted to the signaling region may be delivered to a signalingand/or context control block t91160. The information to be transmittedto the packet stream may be transmitted to the encapsulation part.

The signaling and/or context control block t91160 may collect signalingand/or context information and deliver the collected information to thesignaling manager t91030. In this way, the signaling and/or contextinformation may be transmitted to the signaling region.

The encapsulation part may encapsulate packets in suitable forms suchthat the packets may be delivered to the physical layer. The number ofconfigured encapsulation parts may be the same as the number of IPstreams.

An encapsulation buffer t91170 may receive a packet stream forencapsulation. Packets subjected to overhead reduction may be receivedwhen overhead reduction is performed, and an input IP packet may bereceived without change when overhead reduction is not performed.

An encapsulation control block t91180 may determine whether to performencapsulation on an input packet stream. When encapsulation isperformed, the packet stream may be delivered tosegmentation/concatenation t91190. When encapsulation is not performed,the packet stream may be delivered to a transmission buffer t91230.Whether to perform encapsulation of packets may be determined based onthe signaling information t91010 delivered to the link layer. Thesignaling information t91010 may be delivered to the encapsulationcontrol block t91180 by the scheduler t91020.

In the segmentation/concatenation t91190, the above-descriedsegmentation or concatenation operation may be performed on packets. Inother words, when an input IP packet is longer than a link layer packetcorresponding to an output of the link layer, one IP packet may bedivided into several segments to configure a plurality of link layerpacket payloads. In addition, when the input IP packet is shorter thanthe link layer packet corresponding to the output of the link layer,several IP packets may be combined to configure one link layer packetpayload.

A packet configuration table t91200 may have information about aconfiguration of segmented and/or concatenated link layer packets. Atransmitter and a receiver may have the same information of the packetconfiguration table t91200. The transmitter and the receiver may referto the information of the packet configuration table t91200. An indexvalue of the information of the packet configuration table t91200 may beincluded in headers of the link layer packets.

A link layer header information block t91210 may collect headerinformation generated in an encapsulation process. In addition, the linklayer header information block t91210 may collect information includedin the packet configuration table t91200. The link layer headerinformation block t91210 may configure header information according to aheader configuration of a link layer packet.

A header attachment block t91220 may add headers to payloads of thesegmented and/or concatenated link layer packets. The transmissionbuffer t91230 may function as a buffer for delivering a link layerpacket to a DP t91240 of the physical layer.

Each block or module and parts may be configured as one module/protocolor a plurality of modules/protocols in the link layer.

FIG. 6 illustrates a configuration of a link layer at a receiveraccording to an embodiment of the present invention (normal mode).

The present embodiment is an embodiment presuming that an IP packet isprocessed. The link layer at the receiver may largely include a linklayer signaling part for processing signaling information, an overheadprocessing part, and/or a decapsulation part from a functionalperspective. The link layer at the receiver may further include ascheduler for a control of the entire operation of the link layer andscheduling, input and output parts of the link layer, and/or the like.

First, information received through a physical layer may be delivered tothe link layer. The link layer may process the information to restorethe information to an original state in which the information is not yetprocessed by a transmitter, and deliver the information to an upperlayer. In the present embodiment, the upper layer may be an IP layer.

Information delivered through dedicated channels t92030 separated fromthe physical layer may be delivered to the link layer signaling part.The link layer signaling part may distinguish signaling informationreceived from the physical layer, and deliver the distinguishedsignaling information to each part of the link layer.

A buffer for channels t92040 may function as a buffer that receivessignaling information transmitted through the dedicated channels. Asdescribed above, when physically/logically divided separate channels arepresent in the physical layer, it is possible to receive signalinginformation transmitted through the channels. When the informationreceived from the separate channels is in a divided state, the dividedinformation may be stored until the information is in a complete form.

A signaling decoder/parser t92050 may check a format of signalinginformation received through a dedicated channel, and extractinformation to be used in the link layer.

When the signaling information received through the dedicated channel isencoded, decoding may be performed. In addition, according to a givenembodiment, it is possible to check integrity of the signalinginformation.

A signaling manager t92060 may integrate signaling information receivedthrough several paths. Signaling information received through a DP forsignaling t92070 to be described below may be integrated by thesignaling manager t92060. The signaling manager t92060 may deliversignaling information necessary for each part in the link layer. Forexample, context information for recovery of a packet and the like maybe delivered to the overhead processing part. In addition, signalinginformation for control may be delivered to a scheduler t92020.

General signaling information not received through a separate dedicatedchannel may be received through the DP for signaling t92070. Here, theDP for signaling may refer to a PLS or the like. A reception buffert92080 may function as a buffer for receiving the signaling informationreceived from the DP for signaling t92070. The received signalinginformation may be decapsulated in a decapsulation for signalinginformation block t92090. The decapsulated signaling information may bedelivered to the signaling manager t92060 through a decapsulation buffert92100. As described in the foregoing, the signaling manager t92060 maycollect signaling information and deliver the collected signalinginformation to a desired part in the link layer.

The scheduler t92020 may determine and control operations of severalmodules included in the link layer. The scheduler t92020 may controleach part of the link layer using receiver information t92010 and/orinformation delivered from the signaling manager t92060. In addition,the scheduler t92020 may determine an operation mode and the like ofeach part. Here, the receiver information t92010 may refer toinformation previously stored by the receiver. The scheduler t92020 mayuse information changed by a user such as a channel change and the likefor control.

The decapsulation part may filter a packet received from a DP t92110 ofthe physical layer, and separate the packet based on a type of thepacket. The number of configured decapsulation parts may be the same asthe number of DPs that may be simultaneously decoded in the physicallayer.

A decapsulation buffer t92120 may function as a buffer that receives apacket stream from the physical layer to perform decapsulation. Adecapsulation control block t92130 may determine whether to decapsulatethe received packet stream. When decapsulation is performed, the packetstream may be delivered to a link layer header parser t92140. Whendecapsulation is not performed, the packet stream may be delivered to anoutput buffer t92220. The signaling information delivered from thescheduler t92020 may be used to determine whether to performdecapsulation.

The link layer header parser t92140 may identify a header of a receivedlink layer packet. When the header is identified, it is possible toidentify a configuration of an IP packet included in a payload of thelink layer packet. For example, the IP packet may be segmented orconcatenated.

A packet configuration table t92150 may include payload information oflink layer packets configured through segmentation and/or concatenation.The transmitter and the receiver may have the same information asinformation of the packet configuration table t92150. The transmitterand the receiver may refer to the information of the packetconfiguration table t92150. A value necessary for reassembly may befound based on index information included in the link layer packets.

A reassembly block t92160 may configure payloads of the link layerpackets configured through segmentation and/or concatenation as packetsof an original IP stream. The reassembly block t92160 may reconfigureone IP packet by collecting segments, or reconfigure a plurality of IPpacket streams by separating concatenated packets. The reassembled IPpackets may be delivered to the overhead processing part.

The overhead processing part may perform a reverse process of overheadreduction performed by the transmitter. In the reverse process, anoperation of returning packets experiencing overhead reduction tooriginal packets is performed. This operation may be referred to asoverhead processing. The number of configured overhead processing partsmay be the same as the number of DPs that may be simultaneously decodedin the physical layer.

A packet recovery buffer t92170 may function as a buffer that receivesan RoHC packet or an IP packet decapsulated for overhead processing.

An overhead control block t92180 may determine whether to perform packetrecovery and/or decompression of decapsulated packets. When the packetrecovery and/or decompression are performed, the packets may bedelivered to a packet stream recovery t92190. When the packet recoveryand/or decompression are not performed, the packets may be delivered tothe output buffer t92220. Whether to perform the packet recovery and/ordecompression may be determined based on the signaling informationdelivered by the scheduler t92020.

The packet stream recovery t92190 may perform an operation ofintegrating a packet stream separated from the transmitter and contextinformation of the packet stream. The operation may correspond to aprocess of restoring the packet stream such that the packet stream maybe processed by an RoHC decompressor t92210. In this process, signalinginformation and/or context information may be delivered from a signalingand/or context control block t92200. The signaling and/or contextcontrol block t92200 may distinguish signaling information deliveredfrom the transmitter and deliver the signaling information to the packetstream recovery t92190 such that the signaling information may be mappedto a stream suitable for a context ID.

The RoHC decompressor t92210 may recover headers of packets of a packetstream. When the headers are recovered, the packets of the packet streammay be restored to original IP packets. In other words, the RoHCdecompressor t92210 may perform overhead processing.

The output buffer t92220 may function as a buffer before delivering anoutput stream to an IP layer t92230.

The link layer of the transmitter and the receiver proposed in thepresent invention may include the blocks or modules described above. Inthis way, the link layer may independently operate irrespective of theupper layer and the lower layer, and efficiently perform overheadreduction. In addition, a function which is supportable depending on theupper and lower layers may be easily extended/added/deleted.

FIG. 7 is a diagram illustrating definition according to link layerorganization type according to an embodiment of the present invention.

When a link layer is actually embodied as a protocol layer, a broadcastservice can be transmitted and received through one frequency slot.Here, an example of one frequency slot may be a broadcast channel thatmainly has a specific bandwidth. As described above, according to thepresent invention, in a broadcast system in which a configuration of aphysical layer is changed or in a plurality of broadcast systems withdifferent physical layer configurations, a compatible link layer may bedefined.

The physical layer may have a logical data path for an interface of alink layer. The link layer may access the logical data path of thephysical layer and transmit information associated with thecorresponding data path to the logical data path. The following typesmay be considered as the data path of the physical layer interfaced withthe link layer.

In a broadcast system, a normal data pipe (Normal DP) may exist as atype of data path. The normal data pipe may be a data pipe fortransmission of normal data and may include one or more data pipesaccording to a configuration of a physical layer.

In a broadcast system, a base data pipe (Base DP) may exist as a type ofdata path. The base data pipe may be a data pipe used for specificpurpose and may transmit signaling information (entire or partialsignaling information described in the present invention) and/or commondata in a corresponding frequency slot. As necessary, in order toeffectively manage a bandwidth, data that is generally transmittedthrough a normal data pipe may be transmitted through a base data pipe.When the amount of information to be transmitted when a dedicatedchannel is present exceeds processing capacity of a correspondingchannel, the base data pipe may perform a complementary function. Thatis, data that exceeds the processing capacity of the correspondingchannel may be transmitted through the base data pipe.

In general, the base data pipe continuously uses one designated datapipe. However, one or more data pipes may be dynamically selected forthe base data pipe among a plurality of data pipes using a method suchas physical layer signaling, link layer signaling, or the like in orderto effectively manage a data pipe.

In a broadcast system, a dedicated channel may exist as a type of datapath. The dedicated channel may be a channel used for signaling in aphysical layer or a similar specific purpose and may include a fastinformation channel (FIC) for rapidly acquiring matters that are mainlyserved on a current frequency slot and/or an emergency alert channel(EAC) for immediately transmitting notification of emergency alert to auser.

In general, a logical data path is embodied in a physical layer in orderto transmit the normal data pipe. A logical data path for the base datapipe and/or the dedicated channel may not be embodied in a physicallayer.

A configuration of data to be transmitted in the link layer may bedefined as illustrated in the drawing.

Organization Type 1 may refer to the case in which a logical data pathincludes only a normal data pipe.

Organization Type 2 may refer to the case in which a logical data pathincludes a normal data pipe and a base data pipe.

Organization Type 3 may refer to the case in which a logical data pathincludes a normal data pipe and a dedicated channel.

Organization Type 4 may refer to the case in which a logical data pathincludes a normal data pipe, a data base pipe, and a dedicated channel.

As necessary, the logical data path may include a base data pipe and/ora dedicated channel.

According to an embodiment of the present invention, a transmissionprocedure of signaling information may be determined according toconfiguration of a logical data path. Detailed information of signalingtransmitted through a specific logical data path may be determinedaccording to a protocol of a higher layer of a link layer defined in thepresent invention. Regarding a procedure described in the presentinvention, signaling information parsed through a higher layer may alsobe used and corresponding signaling may be transmitted in the form of anIP packet from the higher layer and transmitted again after beingencapsulated in the form of a link layer packet.

When such signaling information is transmitted, a receiver may extractdetailed signaling information from session information included in anIP packet stream according to protocol configuration. When signalinginformation of a higher layer is used, a database (DB) may be used or ashared memory may be used. For example, in the case of extracting thesignaling information from the session information included in the IPpacket stream, the extracted signaling information may be stored in aDB, a buffer, and/or a shared memory of the receiver. Next, when thesignaling information is needed in a procedure of processing data in abroadcast signal, the signaling information may be obtained from theabove storage device.

FIG. 8 is a diagram illustrating processing of a broadcast signal when alogical data path includes only a normal data pipe according to anembodiment of the present invention.

The diagram illustrates a structure of a link layer when the logical ofthe physical layer includes only a normal data pipe. As described above,the link layer may include a link layer signaling processor, an overheadreduction processor, and an encapsulation (decapsulation) processor.Transmission of information output from each functional module (whichmay be embodied as hardware or software) to an appropriate data path ofthe physical layer may be one of main functions of the link layer.

With regard to an IP stream configured on a higher layer of a linklayer, a plurality of packet streams may be transmitted according to adata rate at which data is to be transmitted, and overhead reduction andencapsulation procedures may be performed for each respectivecorresponding packet stream. A physical layer may include a data pipe(DP) as a plurality of logical data paths that a link layer can accessin one frequency band and may transmit a packet stream processed in alink layer for each respective packet stream. When the number of DPs islower than that of packet streams to be transmitted, some of the packetstreams may be multiplexed and input to a DP in consideration of a datarate.

The signaling processor may check transmission system information,related parameters, and/or signaling transmitted in a higher layer andcollect information to be transmitted via signaling. Since only a normaldata pipe is configured in a physical layer, corresponding signalingneeds to be transmitted in the form of packet. Accordingly, signalingmay be indicated using a header, etc. of a packet during link layerpacket configuration. In this case, a header of a packet includingsignaling may include information for identifying whether signaling datais contained in a payload of the packet.

In the case of service signaling transmitted in the form of IP packet ina higher layer, in general, it is possible to process different IPpackets in the same way. However, information of the corresponding IPpacket can be read for a configuration of link layer signaling. To thisend, a packet including signaling may be found using a filtering methodof an IP address. For example, since IANA designates an IP address of224.0.23.60 as ATSC service signaling, the receiver may check an IPpacket having the corresponding IP address use the IP packet forconfiguration of link layer signaling. In this case, the correspondingpacket needs to also be transmitted to a receiver, processing for the IPpacket is performed without change. The receiver may parse an IP packettransmitted to a predetermined IP address and acquire data for signalingin a link layer.

When a plurality of broadcast services are transmitted through onefrequency band, the receiver does not have to decode all DPs, and it isefficient to pre-check signaling information and to decode only a DPassociated with a required service. Accordingly, with regard to anoperation for a link layer of the receiver, the following procedures maybe performed.

When a user selects or changes a service to be received, the receivertunes a corresponding frequency and reads information of the receiver,stored in a DB, etc. with regard to a corresponding channel.

The receiver checks information about a DP that transmits link layersignaling and decodes the corresponding DP to acquire a link layersignaling packet.

The receiver parses the link layer signaling packet and acquiresinformation about a DP that transmits data associated with a serviceselected by the user among one or more DPs transmitted through a currentchannel and overhead reduction information about a packet stream of thecorresponding DP. The receiver may acquire information foridentification of a DP that transmits the data associated with theservice selected by the user from a link layer signaling packet andobtain a corresponding DP based on the information. In addition, thelink layer signaling packet may include information indicating overheadreduction applied to the corresponding DP, and the receiver may restorea DP to which overhead reduction is applied, using the information.

The receiver transmits DP information to be received, to a physicallayer processor that processes a signal or data in a physical layer andreceives a packet stream from a corresponding DP.

The receiver performs encapsulation and header recovery on the packetstream decoded by the physical layer processor.

Then the receiver performs processing according to a protocol of ahigher layer and provides a broadcast service to the user.

FIG. 9 is a diagram illustrating processing of a broadcast signal when alogical data path includes a normal data pipe and a base data pipeaccording to an embodiment of the present invention.

The diagram illustrates a structure of a link layer when the logicaldata path of the physical layer includes a base data pipe and a normaldata pipe. As described above, the link layer may include a link layersignaling part, an overhead reduction part, and an encapsulation(decapsulation) part. In this case, a link layer processor forprocessing a signal and/or data in a link layer may include a link layersignaling processor, an overhead reduction processor, and anencapsulation (decapsulation) processor.

Transmission of information output from each functional module (whichmay be embodied as hardware or software) to an appropriate data path ofthe physical layer may be one of main functions of the link layer.

With regard to an IP stream configured on a higher layer of a linklayer, a plurality of packet streams may be transmitted according to adata rate at which data is to be transmitted, and overhead reduction andencapsulation procedures may be performed for each respectivecorresponding packet stream.

A physical layer may include a data pipe (DP) as a plurality of logicaldata paths that a link layer can access in one frequency band and maytransmit a packet stream processed in a link layer for each respectivepacket stream. When the number of DPs is lower than that of packetstreams to be transmitted, some of the packet streams may be multiplexedand input to a DP in consideration of a data rate.

The signaling processor may check transmission system information,related parameters, higher layer signaling, etc. and collect informationto be transmitted via signaling. Since a broadcast signal of thephysical layer includes a base DP and a normal DP, signaling may betransmitted to the base DP and signaling data may be transmitted in theform of packet appropriate for transmission of the base DP inconsideration of a data rate. In this case, signaling may be indicatedusing a header, etc. of a packet during link layer packet configuration.For example, a header of a link layer packet may include informationindicating that data contained in a payload of the packet is signalingdata.

In a physical layer structure in which a logical data path such as abase DP exists, it may be efficient to transmit data that is notaudio/video content, such as signaling information to the base DP inconsideration of a data rate. Accordingly, service signaling that istransmitted in the form of IP packet in a higher layer may betransmitted to the base DP using a method such as IP address filtering,etc. For example, IANA designates an IP address of 224.0.23.60 as ATSCservice signaling, an IP packet stream with the corresponding IP addressmay be transmitted to the base DP.

When a plurality of IP packet streams about corresponding servicesignaling is present, the IP packet streams may be transmitted to onebase DP using a method such as multiplexing, etc. However, a packetabout different service signaling may be divided into field values suchas a source address and/or a port. In this case, information requiredfor configuration of link layer signaling can also be read from thecorresponding service signaling packet.

When a plurality of broadcast services are transmitted through onefrequency band, the receiver may not have to decode all DPs, maypre-check signaling information, and may decode only a DP that transmitsdata and/or a signal about a corresponding service. Accordingly, thereceiver may perform the following operation with regard to data and/orprocessing in a link layer.

When a user selects or changes a service to be received, the receivertunes a corresponding frequency and reads information of the receiver,stored in a DB, etc. with regard to a corresponding channel. Here, theinformation stored in the DB, etc. may include information foridentification of the base DP.

The receiver decodes the base DP and acquires a link layer signalingpacket included in the base DP.

The receiver parses the link layer signaling packet to acquire DPinformation for reception of the service selected by the user andoverhead reduction information about a packet stream of thecorresponding DP among a plurality of DPs transmitted through a currentchannel and overhead reduction information about a packet stream of thecorresponding DP. The link layer signaling packet may includeinformation for identification of a DP that transmits a signal and/ordata associated with a specific service, and/or information foridentification of a type of overhead reduction applied to a packetstream transmitted to the corresponding DP. The receiver may access oneor more DPs or restore the packet included in the corresponding DP usingthe above information.

The receiver is a physical layer processor that processes a signaland/or data according to a protocol of a physical layer, transmitsinformation about a DP to be received for a corresponding service, andreceives a packet stream from the corresponding DP.

The receiver performs decapsulation and header recovery on the packetstream decoded in the physical layer and transmits the packet stream toa higher layer of the receiver in the form of IP packet stream.

Then, the receiver performs processing according to a higher layerprotocol and provides a broadcast service to the user.

In the above-described process of acquiring the link layer packet bydecoding the base DP, information about the base DP (e.g., an identifier(ID) information of the base DP, location information of the base DP, orsignaling information included in the base DP) may be acquired duringprevious channel scan and then stored in a DB and the receiver may usethe stored base DP. Alternatively, the receiver may acquire the base DPby first seeking a DP that the receiver has pre-accessed.

In the above-described process of acquiring the DP information for aservice selected by the user and the overhead reduction informationabout a DP packet stream transmitting the corresponding service, byparsing the link layer packet, if the information about the DPtransmitting the service selected by the user is transmitted throughhigher layer signaling (e.g., a layer higher than a link layer, or an IPlayer), the receiver may acquire corresponding information from the DB,the buffer, and/or the shared memory as described above and use theacquired information as information about a DP requiring decoding.

If link layer signaling (link layer signaling information) and normaldata (e.g., broadcast content data) is transmitted through the same DPor if only a DP of one type is used in a broadcast system, the normaldata transmitted through the DP may be temporarily stored in the bufferor the memory while the signaling information is decoded and parsed.Upon acquiring the signaling information, the receiver may transmit acommand for extracting a DP that should be obtained according to thecorresponding signaling information to a device for extracting andprocessing the DP by a method using interior command words of thesystem.

FIG. 10 is a diagram illustrating processing of a broadcast signal whena logical data path includes a normal data pipe and a dedicated channelaccording to an embodiment of the present invention.

The diagram illustrates a structure of a link layer when the logicaldata path of the physical layer includes a dedicated channel and anormal data pipe. As described above, the link layer may include a linklayer signaling part, an overhead reduction part, and an encapsulation(decapsulation) part. In this regard, a link layer processor to beincluded in the receiver may include a link layer signaling processor,an overhead reduction processor, and/or an encapsulation (decapsulation)processor. Transmission of information output from each functionalmodule (which may be embodied as hardware or software) to an appropriatedata path of the physical layer may be one of main functions of the linklayer.

With regard to an IP stream configured on a higher layer of a linklayer, a plurality of packet streams may be transmitted according to adata rate at which data is to be transmitted, and overhead reduction andencapsulation procedures may be performed for each respectivecorresponding packet stream. A physical layer may include a data pipe(DP) as a plurality of logical data paths that a link layer can accessin one frequency band and may transmit a packet stream processed in alink layer for each respective packet stream. When the number of DPs islower than that of packet streams to be transmitted, some of the packetstreams may be multiplexed and input to a DP in consideration of a datarate.

The signaling processor may check transmission system information,related parameters, higher layer signaling, etc. and collect informationto be transmitted via signaling. In a physical layer structure in whicha logical data path such as a dedicate channel exists, it may beefficient to mainly transmit signaling information through a dedicatedchannel in consideration of a data rate. However, when a large amount ofdata needs to be transmitted through a dedicated channel, a bandwidthfor the dedicated channel corresponding to the amount of the dedicatedchannel needs to be occupied, and thus it is general to set a high datarate of the dedicated channel. In addition, since a dedicated channel isgenerally received and decoded at higher speed than a DP, it is moreefficient to signaling data in terms of information that needs to berapidly acquired from the receiver. As necessary, when sufficientsignaling data cannot be transmitted through the dedicated channel,signaling data such as the aforementioned link layer signaling packetmay be transmitted through the normal DP, and signaling data transmittedthrough the dedicated channel may include information for identificationof the corresponding link layer signaling packet.

A plurality of dedicated channels may exist as necessary and a channelmay be enable/disable according to a physical layer.

In the case of service signaling transmitted in the form of IP packet ina higher layer, in general, it is possible to process different IPpackets in the same way. However, information of the corresponding IPpacket can be read for a configuration of link layer signaling. To thisend, a packet including signaling may be found using a filtering methodof an IP address. For example, since IANA designates an IP address of224.0.23.60 as ATSC service signaling, the receiver may check an IPpacket having the corresponding IP address use the IP packet forconfiguration of link layer signaling. In this case, the correspondingpacket needs to also be transmitted to a receiver, processing for the IPpacket is performed without change.

When a plurality of IP packet streams about service signaling ispresent, the IP packet streams may be transmitted to one DP togetherwith audio/video data using a method such as multiplexing, etc. However,a packet about service signaling and audio/video data may be dividedinto field values of an IP address, a port, etc.

When a plurality of broadcast services are transmitted through onefrequency band, the receiver does not have to decode all DPs, and it isefficient to pre-check signaling information and to decode only a DPthat transmit signal and/or data associated with a required service.Thus, the receiver may perform processing according to a protocol of alink layer as the following procedure.

When a user selects or changes a service to be received, the receivertunes a corresponding frequency and reads information stored in a DB,etc. with regard to a corresponding channel. The information stored inthe DB may include information for identification of a dedicated channeland/or signaling information for acquisition of channel/service/program.

The receiver decodes data transmitted through the dedicated channel andperforms processing associated with signaling appropriate for purpose ofthe corresponding channel. For example, a dedicated channel fortransmission of FIC may store and update information such as a serviceand/or a channel, and a dedicated channel for transmission of EAC maytransmit emergency alert information.

The receiver may acquire information of DP to be decoded usinginformation transmitted to the dedicated channel. As necessary, whenlink layer signaling is transmitted through a DP, the receiver maypre-decode a DP that transmits signaling and transmit the DP to adedicated channel in order to pre-acquire signaling information. Inaddition, a packet for link layer signaling may be transmitted through anormal DP, and in this case, the signaling data transmitted through thededicated channel may include information for identification of a DPincluding a packet for link layer signaling.

The receiver acquires DP information for reception of a service selectedby a user among a plurality of DPs that are transmitted to a currentchannel and overhead reduction information about a packet stream of thecorresponding DP using the link layer signaling information. The linklayer signaling information may include information for identificationof a DP for transmission of a signal and/or data associated with aspecific service, and/or information for identification of a type ofoverhead reduction applied to a packet stream transmitted to thecorresponding DP. The receiver may access one or more DPs for a specificservice or restore a packet included in the corresponding DP using theinformation.

The receiver transmits information for identification of a DP to bereceived by a physical layer to a physical layer processor thatprocesses a signal and/or data in a physical layer and receives a packetstream from the corresponding DP.

The receiver performs decapsulation and header recovery on a packetstream decoded in a physical layer and transmits the packet stream to ahigher layer of the receiver in the form of IP packet stream.

Then the receiver performs processing according to a protocol of ahigher layer and provides a broadcast service to the user.

FIG. 11 is a diagram illustrating processing of a broadcast signal whena logical data path includes a normal data pipe, a base data pipe, and adedicated channel according to an embodiment of the present invention.

The diagram illustrates a structure of a link layer when the logicaldata path of the physical layer includes a dedicated channel, a basedata pipe, and a normal data pipe. As described above, the link layermay include a link layer signaling part, an overhead reduction part, andan encapsulation (decapsulation) part. In this regard, a link layerprocessor to be included in the receiver may include a link layersignaling processor, an overhead reduction processor, and/or anencapsulation (decapsulation) processor. Transmission of informationoutput from each functional module (which may be embodied as hardware orsoftware) to an appropriate data path of the physical layer may be oneof main functions of the link layer.

With regard to an IP stream configured on a higher layer of a linklayer, a plurality of packet streams may be transmitted according to adata rate at which data is to be transmitted, and overhead reduction andencapsulation procedures may be performed for each respectivecorresponding packet stream. A physical layer may include a data pipe(DP) as a plurality of logical data paths that a link layer can accessin one frequency band and may transmit a packet stream processed in alink layer for each respective packet stream. When the number of DPs islower than that of packet streams to be transmitted, some of the packetstreams may be multiplexed and input to a DP in consideration of a datarate.

The signaling processor may check transmission system information,related parameters, higher layer signaling, etc. and collect informationto be transmitted via signaling. Since a signal of the physical layerincludes a base DP and a normal DP, it may be efficient to transmitsignaling to the base DP in consideration of a data rate. In this case,the signaling data needs to be transmitted in the form of packetappropriate for transmission through the base DP. Signaling may beindicated using a header, etc. of a packet during link layer packetconfiguration. That is, a header of a link layer signaling packetincluding signaling data may include information indicating thatsignaling data is contained in a payload of the corresponding packet.

In a physical layer structure in which a dedicate channel and a base DPexist simultaneously, signaling information may be divided andtransmitted to the dedicated channel and the base DP. In general, sincea high data rate of the dedicated channel is not set, signalinginformation that has a small amount of signaling and needs to be rapidlyacquired may be transmitted to the dedicated channel and signaling witha high amount of signaling to the base DP. As necessary, a plurality ofdedicated channels may exist and a channel may be enable/disableaccording to a physical layer. In addition, the base DP may beconfigured with a separate structure from a normal DP. In addition, itis possible to designate one of normal DPs and use the normal DP as abase DP.

Service signaling that is transmitted in the form of IP packet in ahigher layer may be transmitted to the base DP using a method such as IPaddress filtering, etc. An IP packet stream with a specific IP addressand including signaling information may be transmitted to the base DP.When a plurality of IP packet streams about corresponding servicesignaling is present, the IP packet streams may be transmitted to onebase DP using a method such as multiplexing, etc. A packet aboutdifferent service signaling may be divided into field values such as asource address and/or a port. The receiver may read information requiredfor configuration of the link layer signaling in the correspondingservice signaling packet.

When a plurality of broadcast services are transmitted through onefrequency band, the receiver may not have to decode all DPs, and it maybe efficient to pre-check the signaling information and to decode only aDP that transmits a signal and/or data associated with a requiredservice. Thus, the receiver may perform the following processors asprocessing according to a protocol of a link layer.

When a user selects or changes a service to be received, the receivertunes a corresponding frequency and reads information stored in adatabase DB, etc. with regard to a corresponding channel. Theinformation stored in the DB may include information for identificationof a dedicated channel, information for identification of a base datapipe, and/or signaling information for acquisition ofchannel/service/program.

The receiver decodes data transmitted through the dedicated channel andperforms processing associated with signaling appropriate for purpose ofthe corresponding channel. For example, a dedicated channel fortransmission of FIC may store and update information such as a serviceand/or a channel, and a dedicated channel for transmission of EAC maytransmit emergency alert information.

The receiver may acquire information of the base DP using informationtransmitted to the dedicated channel. The information transmitted to thededicated channel may include information for identification of the baseDP (e.g., an identifier of the base DP and/or an IP address of the baseDP). As necessary, the receiver may update signaling informationpre-stored in a DB of the receiver and related parameters to informationtransmitted in the dedicated channel.

The receiver may decode the base DP and acquire a link layer signalingpacket. As necessary, the link layer signaling packet may be combinedwith signaling information received from the dedicated channel. Thereceiver may find the base DP using the dedicate channel and thesignaling information pre-stored in the receiver.

The receiver acquires DP information for reception of a service selectedby a user among a plurality of DPs that are transmitted to a currentchannel and overhead reduction information about a packet stream of thecorresponding DP using the link layer signaling information. The linklayer signaling information may include information for identificationof a DP for transmission of a signal and/or data associated with aspecific service, and/or information for identification of a type ofoverhead reduction applied to a packet stream transmitted to thecorresponding DP. The receiver may access one or more DPs for a specificservice or restore a packet included in the corresponding DP using theinformation.

The receiver transmits information for identification of a DP to bereceived by a physical layer to a physical layer processor thatprocesses a signal and/or data in a physical layer and receives a packetstream from the corresponding DP.

The receiver performs decapsulation and header recovery on a packetstream decoded in a physical layer and transmits the packet stream to ahigher layer of the receiver in the form of IP packet stream.

Then the receiver performs processing according to a protocol of ahigher layer and provides a broadcast service to the user.

According to an embodiment of the present invention, when informationfor service signaling is transmitted by one or more IP packet streams,the IP packet streams may be multiplexed and transmitted as one base DP.The receiver may distinguish between packets for different servicesignaling through a field of a source address and/or a port. Thereceiver may read out information for acquiring/configuring link layersignaling from a service signaling packet.

In the process of processing signaling information transmitted throughthe dedicated channel, the receiver may obtain version information ofthe dedicated channel or information identifying whether update has beenperformed and, if it is judged that there is no change in the signalinginformation in the dedicated channel, the receiver may omit processing(decoding or parsing) of the signaling information transmitted throughthe dedicated channel. If it is confirmed that the dedicated channel hasnot been updated, the receiver may acquire information of a base DPusing prestored information.

In the above-described process of acquiring the DP information for aservice selected by the user and the overhead reduction informationabout the DP packet stream transmitting the corresponding service, ifthe information about the DP transmitting the service selected by theuser is transmitted through higher layer signaling (e.g., a layer higherthan a link layer, or an IP layer), the receiver may acquire thecorresponding information from the DB, the buffer, and/or the sharedmemory as described above and use the acquired information asinformation about a DP requiring decoding.

If link layer signaling (link layer signaling information) and normaldata (e.g., broadcast content data) is transmitted through the same DPor if only type of DP is used in a broadcast system, the normal datatransmitted through the DP may be temporarily stored in the buffer orthe memory while the signaling information is decoded and parsed. Uponacquiring the signaling information, the receiver may transmit a commandfor extracting a DP that should be obtained according to thecorresponding signaling information to a device for extracting andprocessing the DP by a method using system interior command words.

FIG. 12 is a diagram illustrating a detailed processing operation of asignal and/or data in a link layer of a receiver when a logical datapath includes a normal data pipe, a base data pipe, and a dedicatedchannel according to an embodiment of the present invention.

The present embodiment considers a situation in which one or moreservices provided by one or more broadcasters are transmitted in onefrequency band. It may be considered that one broadcaster transmits oneor more broadcast services, one service includes one or more componentsand a user receives content in units of broadcast services. In addition,some of one or more components included in one broadcast service may bereplaced with other components according to user selection.

A fast information channel (FIC) and/or emergency alert channel (EAC)may be transmitted to a dedicated channel. A base DP and a normal DP maybe differentiated in a broadcast signal and transmitted or managed.Configuration information of the FIC and/or the EAC may be transmittedthrough physical layer signaling so as to notify the receiver of the FICand/or the EAC, and the link layer may format signaling according to thecharacteristic of the corresponding channel. Transmission of data to aspecific channel of a physical layer is performed from a logical pointof view and an actual operation may be performed according to thecharacteristic of a physical layer.

Information about a service of each broadcaster, transmitted in acorresponding frequency, and information about a path for reception ofthe service may be transmitted through the FIC. To this end, thefollowing information may be provided (signaled) via link layersignaling.

System Parameter—Transmitter related parameter, and/or parameter relatedto a broadcaster that provides a service in a corresponding channel.

Link layer—which includes context information associated with IP headercompression and/or ID of a DP to which corresponding context is applied.

Higher layer—IP address and/or UDP port number, service and/or componentinformation, emergency alert information, and mapping relationinformation between a DP and an IP address of a packet streamtransmitted in an IP layer.

When a plurality of broadcast services is transmitted through onefrequency band, a receiver may not have to decode all DPs, and it may beefficient to pre-check signaling information and to decode only a DPabout a required service. In a broadcast system, a transmitter maytransmit information for identification of only a required DP through anFIC, and the receiver may check a DP to be accessed for a specificserviced, using the FIC. In this case, an operation associated with thelink layer of the receiver may be performed as follows.

When a user selects or changes a service to be received by a user, thereceiver tunes a corresponding frequency and reads information of areceiver, stored in a DB, etc. in regard to a corresponding channel. Theinformation stored in the DB of the receiver may be configured byacquiring an FIC during initial channel scan and using informationincluded in the FIC.

The receiver may receive an FIC and update a pre-stored DB or acquireinformation about a component about a service selected by the user andinformation about a mapping relation for DPs that transmit componentsfrom the FIC. In addition, the information about a base DP thattransmits signaling may be acquired from the FIC.

When initialization information related to robust header compression(RoHC) is present in signaling transmitted through the FIC, the receivermay acquire the initialization information and prepare header recovery.

The receiver decodes a base DP and/or a DP that transmits a serviceselected by a user based on information transmitted through the FIC.

The receiver acquires overhead reduction information about a DP that isbeing received, included in the base DP, performs decapsulation and/orheader recovery on a packet stream received in a normal DP using theacquired overhead information, and transmits the packet stream to ahigher layer of the receiver in the form of IP packet stream.

The receiver may receive service signaling transmitted in the form of IPpacket with a specific address through a base DP and transmit the packetstream to the higher layer with regard to a received service.

When emergency alert occurs, in order to rapidly transmit an emergencyalert message to a user, the receiver receives signaling informationincluded in a CAP message through signaling, parses the signalinginformation, and immediately transmits the signaling information to auser, and finds a path for reception of a corresponding service andreceives service data when information of a path through which anaudio/video service can be received via signaling can be confirmed. Inaddition, when information transmitted through a broadband and so on ispresent, an NRT service and additional information are received usingcorresponding uniform resource identifier (URI) information and so on.Signaling information associated with emergency alert will be describedbelow in detail.

The receiver processes the emergency alert as follows.

The receiver recognizes a situation in which an emergency alert messageis transmitted through a preamble and so on of a physical layer. Thepreamble of the physical layer may be a signaling signal included in abroadcast signal and may correspond to signaling in the physical layer.The preamble of the physical layer may mainly include information foracquisition of data, a broadcast frame, a data pipe, and/or atransmission parameter that are included in a broadcast signal.

The receiver checks configuration of an emergency alert channel (EAC)through physical layer signaling of the receiver and decodes the EAC toacquire EAT. Here, the EAC may correspond to the aforementioneddedicated channel.

The receiver checks the received EAT, extracts a CAP message, andtransmits the CAP message to a CAP parser.

The receiver decodes a corresponding DP and receives service data whenservice information associated with the emergency alert is present inthe EAT. The EAT may include information for identification of a DP fortransmitting a service associated with the emergency alert.

When information associated with NRT service data is present in the EATor the CAP message, the receiver receives the information through abroadband.

FIG. 13 is a diagram illustrating syntax of a fast information channel(FIC) according to an embodiment of the present.

Information included in the FIC may be transmitted in the form of fastinformation table (FIT).

Information included in the FIT may be transmitted in the form of XMLand/or section table.

The FIT may include table_id information, FIT_data_version information,num_broadcast information, broadcast_id information, delivery_system_idinformation, base_DP_id information, base_DP_version information,num_service information, service_id information, service_categoryinformation, service_hidden_flag information, SP_indicator information,num_component information, component_id information, DP_id information,context_id information, RoHC_init_descriptor, context_profileinformation, max_cid information, and/or large_cid information.

The table_id information indicates that a corresponding table sectionrefers to fast information table.

The FIT_data_version information may indicate version information aboutsyntax and semantics contained in the fast information table. Thereceiver may determine whether signaling contained in the correspondingfast information table is processed, using the FIT_data_versioninformation. The receiver may determine whether information ofpre-stored FIC is updated, using the information.

The num_broadcast information may indicate the number of broadcastersthat transmit a broadcast service and/or content through a correspondingfrequency or a transmitted transport frame.

The broadcast_id information may indicate a unique identifier of abroadcaster that transmits a broadcast service and/or content through acorresponding frequency or a transmitted transport frame. In the case ofa broadcaster that transmits MPEG-2 TS-based data, broadcast_id may havea value such as transport_stream_id of MPEG-2 TS.

The delivery_system_id information may indicate an identifier for abroadcast transmission system that applies and processes the sametransmission parameter on a broadcast network that performstransmission.

The base_DP_id information is information for identification of a baseDP in a broadcast signal. The base DP may refer to a DP that transmitsservice signaling including overhead reduction and/or program specificinformation/system information (PSI/SI) of a broadcaster correspondingto broadcast_id. Alternatively, the base_DP_id information may refer toa representative DP that can decode a component included in a broadcastservice in the corresponding broadcaster.

The base_DP_version information may refer to version information aboutdata transmitted through a base DP. For example, when service signalingsuch as PSI/SI and so on is transmitted through the base DP, if servicesignaling is changed, a value of the base_DP_version information may beincreased one by one.

The num_service information may refer to the number of broadcastservices transmitted from a broadcaster corresponding to thebroadcast_id in a corresponding frequency or a transport frame.

The service_id information may be used as an identifier foridentification of a broadcast service.

The service_category information may refer to a category of a broadcastservice. According to a value of a corresponding field, theservice_category information may have the following meaning. When avalue of the service_category information is 0×01, the service_categoryinformation may refer to a basic TV, when the value of theservice_category information is 0×02, the service_category informationmay refer to a basic radio, when the value of the service_categoryinformation is 0×03, the service_category information may refer to an RIservice, when the value of the service_category information is 0×08, theservice_category information may refer to a service guide, and when thevalue of the service_category information is 0×09, the service_categoryinformation may refer to emergency alerting.

The service_hidden_flag information may indicate whether a correspondingbroadcast service is hidden. When the service is hidden, the broadcastservice may be a test service or a self-used service and may beprocessed to be disregarded or hidden from a service list by a broadcastreceiver.

The SP_indicator information may indicate whether service protection isapplied to one or more components in a corresponding broadcast service.

The num_component information may indicate the number of componentsincluded in a corresponding broadcast service.

The component_id information may be used as an identifier foridentification of a corresponding component in a broadcast service.

The DP_id information may be used as an identifier indicating a DP thattransmits a corresponding component.

The RoHC_init_descriptor may include information associated withoverhead reduction and/or header recovery. The RoHC_init_descriptor mayinclude information for identification of a header compression methodused in a transmission terminal.

The context_id information may represent a context corresponding to afollowing RoHC related field. The context_id information may correspondto a context identifier (CID).

The context_profile information may represent a range of a protocol forcompression of a header in RoHC. When a compressor and a decompressorhave the same profile, it is possible to compress and restore a streamin the RoHC.

The max_cid information is used for indicating a maximum value of a CIDto a decompressor.

The large_cid information has a boolean value and indicates whether ashort CID (0 to 15) or an embedded CID (0 to 16383) is used for CIDconfiguration. Accordingly, the sized of byte for representing the CIDis determined together.

FIG. 14 is a diagram illustrating syntax of an emergency alert table(EAT) according to an embodiment of the present invention.

Information associated with emergency alert may be transmitted throughthe EAC. The EAC may correspond to the aforementioned dedicated channel.

The EAT according to an embodiment of the present invention may includeEAT_protocol_version information, automatic_tuning_flag information,num_EAS_messages information, EAS_message_id information,EAS_IP_version_flag information, EAS_message_transfer_type information,EAS_message_encoding_type information, EAS_NRT_flag information,EAS_message_length information, EAS_message_byte information, IP_addressinformation, UDP_port_num information, DP_id information,automatic_tuning_channel_number information, automatic_tuning_DP_idinformation, automatic_tuning_service_id information, and/orEAS_NRT_service_id information.

The EAT_protocol_version information indicates a protocol version ofreceived EAT.

The automatic_tuning_flag information indicates whether a receiverautomatically performs channel conversion.

The num_EAS_messages information indicates the number of messagescontained in the EAT.

The EAS_message_id information is information for identification of eachEAS message.

The EAS_IP_version_flag information indicates IPv4 when a value of theEAS_IP_version_flag information is 0, and indicates IPv6 when a value ofthe EAS_IP_version_flag information is 1.

The EAS_message_transfer_type information indicates the form in which anEAS message is transmitted. When a value of theEAS_message_transfer_type information is 000, theEAS_message_transfer_type information indicates a not specified state,when a value of the EAS_message_transfer_type information is 001, theEAS_message_transfer_type information indicates a no alert message (onlyAV content), and when a value of the EAS_message_transfer_typeinformation is 010, the EAS_message_transfer_type information indicatesthat an EAS message is contained in corresponding EAT. To this end, alength field and a field about the corresponding EAS message are added.When a value of the EAS_message_transfer_type information is 011, theEAS message transfer type information indicates that the EAS message istransmitted through a data pipe. The EAS may be transmitted in the formof IP datagram in a data pipe. To this end, IP address, UDP portinformation, and DP information of a transmitted physical layer may beadded.

The EAS_message_encoding_type information indicates information about anencoding type of an emergence alert message. For example, when a valueof the EAS_message_encoding_type information is 000, theEAS_message_encoding_type information indicates a not specific state,when a value of the EAS_message_encoding_type information is 001, theEAS_message_encoding_type information indicates No Encoding, when avalue of the EAS_message_encoding_type information is 010, theEAS_message_encoding_type information indicates DEFLATE algorithm(RFC1951), and 001 to 111 among values of the EAS_message_encoding_typeinformation may be reserved for other encoding types.

The EAS_NRT_flag information indicates whether NRT contents and/or NRTdata associated with a received message is present. When a value of theEAS_NRT_flag information is 0, the EAS_NRT_flag information indicatesthat NRT contents and/or NRT data associated with a received emergencymessage is not present, and when a value of the EAS_NRT_flag informationis 1, the EAS_NRT_flag information indicates that NRT contents and/orNRT data associated with a received emergency message is present.

The EAS_message_length information indicates a length of an EAS message.

The EAS_message_byte information includes content of an EAS message.

The IP_address information indicates an IP address of an IP address fortransmission of an EAS_message.

The UDP_port_num information indicates a UDP port number fortransmission of an EAS_message.

The DP_id information identifies a data pipe that transmits anEAS_message.

The automatic_tuning_channel_number information includes informationabout a number of a channel to be converted.

The automatic_tuning_DP_id information is information for identificationof a data pipe that transmits corresponding content.

The automatic_tuning_service_id information is information foridentification of a service to which corresponding content belongs.

The EAS_NRT_service_id information is information for identification ofan NRT service corresponding to the case in which NRT contents and dataassociated with a received emergency alert message and transmitted, thatis, the case in which an EAS_NRT_flag is enabled.

FIG. 15 is a diagram illustrating a packet transmitted to a data pipeaccording to an embodiment of the present invention.

According to an embodiment of the present invention, configuration of apacket in a link layer is newly defined so as to generate a compatiblelink layer packet irrespective of change in protocol of a higher layeror the link layer or a lower layer of the link layer.

The link layer packet according to an embodiment of the presentinvention may be transmitted to a normal DP and/or a base DP.

The link layer packet may include a fixed header, an expansion header,and/or a payload.

The fixed header is a header with a fixed size and the expansion headeris a header, the size of which can be changed according to configurationof the packet of the higher layer. The payload is a region in which dataof the higher layer is transmitted.

A header (the fixed header or the expansion header) of a packet mayinclude a field indicating a type of the payload of the packet. In thecase of the fixed header, first 3 bits (packet type) of 1 byte mayinclude data for identification of a packet type of the higher layer,and the remaining 5 bits may be used as an indicator part. The indicatorpart may include data for identification of a configuring method of apayload and/or configuration information of the expansion header and maybe changed according to a packet type.

A table shown in the diagram represents a type of a higher layerincluded in a payload according to a value of a packet type.

According to system configuration, an IP packet and/or an RoHC packet ofthe payload may be transmitted through a DP, and a signaling packet maybe transmitted through a base DP. Accordingly, when a plurality ofpackets are mixed and transmitted, packet type values may also beapplied so as to differentiate a data packet and a signaling packet.

When a packet type value is 000, an IP packet of IPv4 is included in apayload.

When a packet type value is 001, an IP packet of IPv6 is included in apayload.

When a packet type value is 010, a compressed IP packet is included in apayload. The compressed IP packet may include an IP packet to whichheader compression is applied.

When a packet type value is 110, a packet including signaling data isincluded in a payload.

When a packet type value is 111, a framed packet type is included in apayload.

FIG. 16 is a diagram illustrating a detailed processing operation of asignal and/or data in each protocol stack of a transmitter when alogical data path of a physical layer includes a dedicated channel, abase DP, and a normal data DP, according to another embodiment of thepresent invention.

In one frequency band, one or more broadcasters may provide broadcastservices. A broadcaster transmits multiple broadcast services and onebroadcast service may include one or more components. A user may receivecontent in units of broadcast services.

In a broadcast system, a session-based transmission protocol may be usedto support IP hybrid broadcast and the contents of signaling deliveredto each signaling path may be determined according to the structure ofthe corresponding transmission protocol.

As described above, data related to the FIC and/or the EAC may betransmitted/received over the dedicated channel. In the broadcastsystem, a base DP and a normal DP may be used to distinguishtherebetween.

Configuration information of the FIC and/or EAC may be included inphysical layer signaling (or a transmission parameter). A link layer mayformat signaling according to characteristics of a correspondingchannel. Transmission of data to a specific channel of a physical layermay be performed from a logical point of view and actual operation maybe performed according to characteristics of a physical layer.

The FIC may include information about services of each broadcaster,transmitted in a corresponding frequency and information about paths forreceiving the services. The FIC may include information for serviceacquisition and may be referred to as service acquisition information.

The FIC and/or the EAC may be included in link layer signaling.

Link layer signaling may include the following information.

System Parameter—A parameter related to a transmitter or a parameterrelated to a broadcaster that provides a service in a correspondingchannel.

Link layer—Context information associated with IP header compression andan ID of a DP to which a corresponding context is applied.

Higher layer—IP address and UDP port number, service and componentinformation, emergency alert information, and a mapping relationshipbetween an ID address, a UDP port number, a session ID, and a DP of apacket stream and signaling transmitted in an IP layer.

As described above, one or more broadcast services are transmitted inone frequency band, the receiver does not need to decode all DPs and itis efficient to pre-check signaling information and to decode only a DPrelated to a necessary service.

In this case, referring to the drawing, the broadcast system may provideand acquire information for mapping a DP and a service, using the FICand/or the base DP.

A process of processing a broadcast signal or broadcast data in atransmitter of the drawing will now be described. One or morebroadcasters (broadcasters #1 to # N) may process component signalingand/or data for one or more broadcast services so as to be transmittedthrough one or more sessions. One broadcast service may be transmittedthrough one or more sessions. The broadcast service may include one ormore components included in the broadcast service and/or signalinginformation for the broadcast service. Component signaling may includeinformation used to acquire components included in the broadcast servicein a receiver. Service signaling, component signaling, and/or data forone or more broadcast services may be transmitted to a link layerthrough processing in an IP layer.

In the link layer, the transmitter performs overhead reduction whenoverhead reduction for an IP packet is needed and generates relatedinformation as link layer signaling. Link layer signaling may include asystem parameter specifying the broadcast system, in addition to theabove-described information. The transmitter may process an IP packet ina link layer processing procedure and transmit the processed IP packetto a physical layer in the form of one or more DPs.

The transmitter may transmit link layer signaling to the receiver in theform or configuration of an FIC and/or an EAC. Meanwhile, thetransmitter may also transmit link layer signaling to the base DPthrough an encapsulation procedure of the link layer.

FIG. 17 is a diagram illustrating a detailed processing operation of asignal and/or data in each protocol stack of a receiver when a logicaldata path of a physical layer includes a dedicated channel, a base DP,and a normal data DP, according to another embodiment of the presentinvention.

If a user selects or changes a service desired to be received, areceiver tunes to a corresponding frequency. The receiver readsinformation stored in a DB etc. in association with a correspondingchannel. The information stored in the DB etc. of the receiver may beinformation included upon acquiring an FIC and/or an EAC during initialchannel scan. Alternatively, the receiver may extract transmittedinformation as described above in this specification.

The receiver may receive the FIC and/or the EAC, receive informationabout a channel that the receiver desires to access, and then updateinformation pre-stored in the DB. The receiver may acquire componentsfor a service selected by a user and information about a mappingrelationship of a DP transmitted by each component or acquire a base DPand/or a normal DP through which signaling necessary to obtain suchinformation is transmitted. Meanwhile, when it is judged that there isno change in corresponding information using version information of theFIC or information identifying whether to require additional update of adedicated channel, the receiver may omit a procedure of decoding orparsing the received FIC and/or EAC.

The receiver may acquire a link layer signaling packet including linklayer signaling information by decoding a base DP and/or a DP throughwhich signaling information is transmitted, based on informationtransmitted through the FIC. The receiver may use, when necessary, thereceived link layer signaling information by a combination withsignaling information (e.g., receiver information in the drawing)received through the dedicated channel.

The receiver may acquire information about a DP for receiving a serviceselected by the user among multiple DPs that are being transmitted overa current channel and overhead reduction information about a packetstream of the corresponding DP, using the FIC and/or the link layersignaling information.

When the information about the DP for receiving the selected service istransmitted through higher layer signaling, the receiver may acquiresignaling information stored in the DB and/or the shared memory asdescribed above and then acquire information about a DP to be decoded,indicated by the corresponding signaling information.

When the link layer signaling information and normal data (e.g., dataincluded in broadcast content) are transmitted through the same DP oronly one DP is used for transmission of the link layer signalinginformation and normal data, the receiver may temporarily store thenormal data transmitted through the DP in a device such as a bufferwhile the signaling information is decoded and/or parsed.

The receiver may acquire the base DP and/or the DP through which thesignaling information is transmitted, acquire overhead reductioninformation about a DP to be received, perform decapsulation and/orheader recovery for a packet stream received in a normal DP, using theacquired overhead information, process the packet stream in the form ofan IP packet stream, and transmit the IP packet stream to a higher layerof the receiver.

FIG. 18 is a diagram illustrating a syntax of an FIC according toanother embodiment of the present invention.

Information included in the FIC described in this drawing may beselectively combined with other information included in the FIC and mayconfigure the FIC.

The receiver may rapidly acquire information about a channel, using theinformation included in the FIC. The receiver may acquire bootstraprelated information using the information included in the FIC. The FICmay include information for fast channel scan and/or fast serviceacquisition. The FIC may be referred to by other names, for example, aservice list table or service acquisition information. The FIC may betransmitted by being included in an IP packet in an IP layer accordingto a broadcast system. In this case, an IP address and/or a UDP portnumber, transmitting the FIC, may be fixed to specific values and thereceiver may recognize that the IP packet transmitted with thecorresponding IP address and/or UDP port number includes the FIC,without an additional processing procedure.

The FIC may include FIC_protocol_version_information,transport_stream_id information, num_partitions information,partition_id information, partition_protocol_version information,num_services information, service_id information, service_data_versioninformation, service_channel_number information, service_categoryinformation, service_status information, service_distributioninformation, sp_indicator information, IP_version_flag information,SSC_source_P_address_flag information, SSC_source_IP_addressinformation, SSC_destination_IP_address information,SSC_destination_UDP_port information, SSC_TSI information, SSC_DP_IDinformation, num_partition_level_descriptors information,partition_level_descriptor( ) information, num_FIC_level_descriptorsinformation, and/or FIC_level_descriptor( ) information.

FIC_protocol_version information represents a version of a protocol ofan FIC.

transport_stream_id information identifies a broadcast stream.transport_stream_id information may be used as information foridentifying a broadcaster.

num_partitions information represents the number of partitions in abroadcast stream. The broadcast stream may be transmitted after beingdivided into one or more partitions. Each partition may include one ormore DPs. The DPs included in each partition may be used by onebroadcaster. In this case, the partition may be defined as a datatransmission unit allocated to each broadcaster.

partition_id information identifies a partition. partition_idinformation may identify a broadcaster.

partition_protocol_version information represents a version of aprotocol of a partition.

num_services information represents the number of services included in apartition. A service may include one or more components.

service_id information identifies a service.

service_data_version information represents change when a signalingtable (signaling information) for a service is changed or a serviceentry for a service signaled by an FIC is changed. service_data_versioninformation may increment a value thereof whenever such change ispresent.

service_channel_number information represents a channel number of aservice.

service_category information represents a category of a service. Thecategory of a service includes A/V content, audio content, an electronicservice guide (ESG), and/or content on demand (CoD).

service_status information represents a state of a service. A state of aservice may include an active or suspended state and a hidden or shownstate. The state of a service may include an inactive state. In theinactive state, broadcast content is not currently provided but may beprovided later. Accordingly, when a viewer scans a channel in areceiver, the receiver may not show a scan result for a correspondingservice to the viewer.

service_distribution information represents a distribution state of datafor a service. For example, service_distribution information mayrepresent that entire data of a service is included in one partition,partial data of a service is not included in a current partition butcontent is presentable only by data in this partition, another partitionis needed to present content, or another broadcast stream is needed topresent content.

sp_indicator information identifies whether service protection has beenapplied. sp_indicator information may identify, for example, formeaningful presentation, whether one or more necessary components areprotected (e.g., a state in which a component is encrypted).

IP_version_flag information identifies whether an IP address indicatedby SSC_source_IP_address information and/or SSC_destination_IP_addressinformation is an IPv4 address or an IPv6 address.

SSC_source_IP_address_flag information identifies whetherSSC_source_IP_address information is present.

SSC_source_IP_address information represents a source IP address of anIP datagram that transmits signaling information for a service. Thesignaling information for a service may be referred to as service layersignaling. Service layer signaling includes information specifying abroadcast service. For example, service layer signaling may includeinformation identifying a data unit (a session, a DP, or a packet) thattransmits components constituting a broadcast service.

SSC_destination_IP_address information represents a destination IPaddress of an IP datagram (or channel) that transmits signalinginformation for a service.

SSC_destination_UDP_port information represents a destination UDP portnumber for a UDP/IP stream that transmits signaling information for aservice.

SSC_TSI information represents a transport session identifier (TSI) ofan LCT channel (or session) that transmits signaling information (or asignaling table) for a service.

SSC_DP_ID information represents an ID for identifying a DP includingsignaling information (or a signaling table) for a service. As a DPincluding the signaling information, the most robust DP in a broadcasttransmission process may be allocated.

num_partition_level descriptor( ) information identifies the number ofdescriptors of a partition level for a partition.

partition_level_descriptor( ) information includes zero or moredescriptors that provide additional information for a partition.

num_FIC_level_descriptors information represents the number ofdescriptors of an FIC level for an FIC.

FIC_level_descriptor( ) information includes zero or more descriptorsthat provide additional information for an FIC.

FIG. 19 is a diagram illustrating signaling_Information_Part( )according to an embodiment of the present invention.

A broadcast system may add additional information to an extended headerpart in the case of a packet for transmitting signaling information in astructure of a packet transmitted through the above-described DP. Suchadditional information will be referred to asSignaling_Information_Part( ).

Signaling_Information_Part( ) may include information used to determinea processing module (or processor) for received signaling information.In a system configuration procedure, the broadcast system may adjust thenumber of fields indicating information and the number of bits allocatedto each field, in a byte allocated to Signaling_Information_Part( ).When signaling information is transmitted through multiplexing, areceiver may use information included in Signaling_Information_Part( )to determine whether corresponding signaling information is processedand determine to which signaling processing module signaling informationshould be transmitted.

Signaling_Information_Part( ) may include Signaling_Class information,Information_Type information, and/or signaling format information.

Signaling_Class information may represent a class of transmittedsignaling information. Signaling information may correspond to an FIC,an EAC, link layer signaling information, service signaling information,and/or higher layer signaling information. Mapping for a class ofsignaling information indicated by each value of configuration of thenumber of bits of a field of Signaling_Class information may bedetermined according to system design.

Information_Type information may be used to indicate details ofsignaling information identified by signaling class information. Meaningof a value indicated by Information_Type information may be additionallydefined according to class of signaling information indicated bySignaling_Class information.

Signaling format information represents a form (or format) of signalinginformation configured in a payload. The signaling format informationmay identify formats of different types of signaling informationillustrated in the drawing and identify a format of additionallydesignated signaling information.

Signaling_Information_Part( ) of (a) and (b) illustrated in the drawingis one embodiment and the number of bits allocated to each field thereofmay be adjusted according to characteristics of the broadcast system.

Signaling_Information_Part( ) as in (a) of the drawing may includesignaling class information and/or signaling format information.Signaling_Information_Part( ) may be used when a type of signalinginformation need not be designated or an information type can be judgedin signaling information. Alternatively, when only one signaling formatis used or when an additional protocol for signaling is present so thatsignaling formats are always equal, only a 4-bit signaling class fieldmay be used without configuring a signaling field and the other fieldsmay be reserved for later use or an 8-bit signaling class maybeconfigured to support various types of signaling.

Signaling_Information_Part( ) as in (b) of the drawing may furtherinclude information type information for indicating a type orcharacteristic of more detailed information in a signaling class whenthe signaling class is designated and may also include signaling formatinformation. Signaling class information and information typeinformation may be used to determine decapsulation of signalinginformation or a processing procedure of corresponding signaling. Adetailed structure or processing of link layer signaling may refer tothe above description and a description which will be given below.

FIG. 20 is a diagram illustrating a procedure for controlling anoperation mode of a transmitter and/or a receiver in a link layeraccording to an embodiment of the present invention.

When the operation mode of the transmitter or the receiver of the linklayer is determined, a broadcast system can be more efficiently used andcan be flexibly designed. The method of controlling the link layer modeproposed according to the present invention can dynamically convert amode of a link layer in order to efficiently manage a system bandwidthand processing time. In addition, the method of controlling the linklayer mode according to the present invention may easily cope with thecase in which a specific mode needs to be supported due to change in aphysical layer or on the other hand, the specific mode does not have tobe changed any more. In addition, the method of controlling the linklayer mode according to the present invention may also allow a broadcastsystem to easily satisfy requirements of a corresponding broadcasterwhen a broadcaster providing a broadcast service intends to designate amethod of transmitting a corresponding service.

The method of controlling the mode of the link layer may be configuredto be performed only in a link layer or to be performed via change indata configuration in the link layer. In this case, it is possible toperform an independent operation of each layer in a network layer and/ora physical layer without embodiment of a separate function. In the modeof the link layer proposed according to the present invention, it ispossible to control the mode with signaling or parameters in a systemwithout changing a system in order to satisfy configuration of aphysical layer. A specific mode may be performed only when processing ofcorresponding input is supported in a physical layer.

The diagram is a flowchart illustrating processing of signal and/or datain an IP layer, a link layer, and a physical layer by a transmitterand/or a receiver.

A function block (which may be embodied as hardware and/or software) formode control may be added to the link layer and may manage parameterand/or signaling information for determination of whether a packet isprocessed. The link layer may determine whether a corresponding functionis performed during processing of a packet stream using information of amode control functional block.

First, an operation of the transmitter will be described.

When an IP is input to a link layer, the transmitter determines whetheroverhead reduction (j16020) is performed using a mode control parameter(j16005). The mode control parameter may be generated by a serviceprovider in the transmitter. The mode control parameter will bedescribed below in detail.

When the overhead reduction (j16020) is performed, information aboutoverhead reduction is generated and is added to link layer signaling(j16060) information. The link layer signaling (j16060) information mayinclude all or some of mode control parameters. The link layer signaling(j16060) information may be transmitted in the form of link layersignaling packet. The link layer signaling packet may be mapped to a DPand transmitted to the receiver, but may not be mapped to the DP and maybe transmitted to the receiver in the form of link layer signalingpacket through a predetermined region of a broadcast signal.

A packet stream on which the overhead reduction (j16020) is performed isencapsulated (j16030) and input to a DP of a physical layer (j16040).When overhead reduction is not performed, whether encapsulation isperformed is re-determined (j16050).

A packet stream on which the encapsulation (j16030) is performed isinput to a DP (j16040) of a physical layer. In this case, the physicallayer performs an operation for processing a general packet (a linklayer packet). When overhead reduction and encapsulation are notperformed, an IP packet is transmitted directly to a physical layer. Inthis case, the physical layer performs an operation for processing theIP packet. When the IP packet is directly transmitted, a parameter maybe applied to perform the operation only when the physical layer supportIP packet input. That is, a value of a mode control parameter may beconfigured to be adjusted such that a process of transmitting an IPpacket directly to a physical layer is not performed when the physicallayer does not support processing of an IP packet.

The transmitter transmits a broadcast signal on which this process isperformed, to the receiver.

An operation of the receiver will be described below.

When a specific DP is selected for the reason such channel change and soon according to user manipulation and a corresponding DP receives apacket stream (j16110), the receiver may check a mode in which a packetis generated, using a header and/or signaling information of the packetstream (j16120). When the operation mode during transmission of thecorresponding DP is checked, decapsulation (j16130) and overheadreduction (j16140) processes are performed through a receiving operatingprocess of a link layer and then an IP packet is transmitted to a higherlayer. The overhead reduction (j16140) process may include an overheadrecovery process.

FIG. 21 is a diagram illustrating an operation in a link layer accordingto a value of a flag and a type of a packet transmitted to a physicallayer according to an embodiment of the present invention.

In order to determine an operation mode of the link layer, theaforementioned signaling method may be used. Signaling informationassociated with the method may be transmitted directly to a receiver. Inthis case, the aforementioned signaling data or link layer signalingpacket may include mode control that will be described below and relatedinformation.

In consideration of the complexity of the receiver, an operation mode ofthe link layer may be indirectly indicated to the receiver.

The following two flags may be configured with regard to control of anoperation mode.

Header compression flag (HCF): This may be a flag for determination ofwhether header compression is applied to a corresponding link layer andmay have a value indicating enable or disable.

Encapsulation flag (EF): This may be a flag for determination of whetherencapsulation is applied in a corresponding link layer and may have avalue indicating enable or disable. However, when encapsulation needs tobe performed according to a header compression scheme, the EF may bedefined to be dependent upon a HCF.

A value mapped to each flag may be applied according to systemconfiguration as long as the value represents Enable and Disable, and abit number allocated to each flag can be changed. According to anembodiment of the present invention, an enable value may be mapped to 1and a disable value may be mapped to 0.

The diagram shows whether header compression and encapsulation includedin a link layer are performed according to values of HCF and EF and inthis case, a packet format transmitted to a physical layer. That is,according to an embodiment of the present invention, the receiver canknow a type of a packet input to the physical layer as information aboutthe HCF and the EF.

FIG. 22 is a diagram a descriptor for signaling a mode control parameteraccording to an embodiment of the present invention.

Flags as information about mode control in a link layer may be signalinginformation, generated by the transmitter in the form of descriptor, andtransmitted to the receiver. Signaling including a flag as informationabout mode control may be used to control an operation mode in atransmitter of a headend terminal, and whether a flag as informationabout mode control is included in signaling transmitted to the receivermay be optionally selected.

When signaling including a flag as information about mode control istransmitted to the receiver, the receiver may directly select anoperation mode about a corresponding DP and perform a packetdecapsulation operation. When signaling including a flag as informationabout mode control is not transmitted to the receiver, the receiver candetermine a mode in which the signaling is transmitted, using physicallayer signaling or field information of a packet header, which istransmitted to the receiver.

The link layer mode control description according to an embodiment ofthe present invention may include DP_id information, HCF information,and/or EF information. The link layer mode control description may beincluded in a transmission parameter in the aforementioned FIC, linklayer signaling packet, signaling via a dedicated channel, PSI/SI,and/or physical layer.

The DP_id information identifies a DP to which a mode in a link layer isapplied.

The HCF information identifies whether header compression is applied inthe DP identified by the DP_id information.

The EF information identifies whether encapsulation is performed on theDP identified by the DP_id information.

FIG. 23 is a diagram illustrating an operation of a transmitter forcontrolling an operation mode according to an embodiment of the presentinvention.

Although not illustrated in the diagram, prior to a processing processof al ink layer, a transmitter may perform processing in a higher layer(e.g., an IP layer). The transmitter may generate an IP packet includingbroadcast data for a broadcast service.

The transmitter parses or generates a system parameter (JS19010). Here,the system parameter may correspond to the aforementioned signaling dataand signaling information.

The transmitter may receive or set mode control related parameter orsignaling information during a broadcast data processing process in alink layer and sets a flag value associated with operation mode control(JS19020). The transmitter may perform this operation after the headercompression operation or the encapsulation operation. That is, thetransmitter may perform the header compression or encapsulationoperation and generate information associated with this operation.

The transmitter acquires a packet of a higher layer that needs to betransmitted through a broadcast signal (JS19030). Here, the packet ofthe higher layer may correspond to an IP packet.

The transmitter checks HCF in order to determine whether headercompression is applied to the packet of the higher layer (JS19040).

When the HCF is enabled, the transmitter applies the header compressionto the packet of the higher layer (JS19050). After header compression isperformed, the transmitter may generate the HCF. The HCF may be used tosignal whether header compression is applied, to the receiver.

The transmitter performs encapsulation on the packet of the higher layerto which header compression is applied to generate a link layer packet(JS19060). After the encapsulation process is performed, the transmittermay generate an EF. The EF may be used to signal whether encapsulationis applied to the higher layer packet, to the receiver.

The transmitter transmits the link layer packet to a physical layerprocessor (JS19070). Then the physical layer processor generates abroadcast signal including the link layer packet and transmits thebroadcast signal to the receiver.

When the HCF is disabled, the transmitter checks the EF in order todetermine whether encapsulation is applied (JS19080).

When the EF is enabled, the transmitter performs encapsulation on thehigher layer packet (JS19090). When the EF is disabled, the transmitterdoes not perform separate processing on the corresponding packet stream.The transmitter transmits the packet stream (link layer packet) on whichprocessing is completed in the link layer, to a physical layer(JS19070). Header compression, encapsulation, and/or generation of linklayer may be performed by a link layer packet generator (i.e. link layerprocessor) in the transmitter.

The transmitter may generate service signaling channel (SCC) data. Theservice signaling channel data may be generated by a service signalingdata encoder. The service signaling data encoder may be included in alink layer processor and may present separately from the link layerprocessor. The service signaling channel data may include theaforementioned FIC and/or EAT. The service signaling channel data may betransmitted to the aforementioned dedicated channel.

FIG. 24 is a diagram illustrating an operation of a receiver forprocessing a broadcast signal according to an operation mode accordingto an embodiment of the present invention.

A receiver may receive information associated with an operation mode ina link layer together with a packet stream.

The receiver receives signaling information and/or channel information(JS20010). Here, a description of the signaling information and/or thechannel information is replaced with the above description.

The receiver selects a DP for receiving and processing according to thesignaling information and/or the channel information (JS20020).

The receiver performs decoding of a physical layer on the selected DPand receives a packet stream of a link layer (JS20030).

The receiver checks whether link layer mode control related signaling isincluded in the received signaling (JS20040).

When the receiver receives the link layer mode related information, thereceiver checks an EF (JS20050).

When the EF is enabled, the receiver performs a decapsulation process ona link layer packet (JS20060).

The receiver checks an HCF after decapsulation of the packet, andperforms a header decompression process when the HCF is enabled(JS20080).

The receiver transmits the packet on which header decompression isperformed, to a higher layer (e.g., an IP layer) (JS20090). During theaforementioned process, when the HCF and the EF are disabled, thereceiver recognizes the processed packet stream as an IP packet andtransmits the corresponding packet to the IP layer.

When the receiver does not receive link layer mode related informationor a corresponding system does not transmit the link layer mode relatedinformation to the receiver, the following operation is performed.

The receiver receives signaling information and/or channel information(JS20010) and selects a DP for reception and processing according tocorresponding information (JS20020). The receiver performs decoding ofthe physical layer on the selected DP to acquire a packet stream(JS20030).

The receiver checks whether the received signaling includes link layermode control related signaling (JS20040).

Since the receiver does not receive link layer mode related signaling,the receiver checks a format of the packet transmitted using physicallayer signaling, etc. (JS20100). Here, the physical layer signalinginformation may include information for identification of a type of thepacket included in a payload of the DP. When the packet transmitted fromthe physical layer is an IP packet, the receiver transmits the packet tothe IP layer without a separate process in a link layer.

When a packet transmitted from a physical layer is a packet on whichencapsulation is performed, the receiver performs a decapsulationprocess on the corresponding packet (JS20110).

The receiver checks the form of a packet included in a payload usinginformation such as a header, etc. of the link layer packet during thedecapsulation process (JS20120), and the receiver transmits thecorresponding packet to the IP layer processor when the payload is an IPpacket.

When the payload of the link layer packet is a compressed IP, thereceiver performs a decompression process on the corresponding packet(JS20130).

The receiver transmits the IP packet to an IP layer processor (JS20140).

FIG. 25 is a diagram illustrating information for identifying anencapsulation mode according to an embodiment of the present invention.

In a broadcast system, when processing in a link layer operates in oneor more modes, a procedure for determining as which mode processing inthe link layer operates (in a transmitter and/or a receiver) may beneeded. In a procedure of establishing a transmission link between thetransmitter and the receiver, the transmitter and/or the receiver mayconfirm configuration information of the link layer. This case maycorrespond to the case in which the receiver is initially set up orperforms a scan procedure for a service or a mobile receiver newlyenters an area within a transmission radius of the transmitter. Thisprocedure may be referred to as an initialization procedure or abootstrapping procedure. This procedure may be configured as a partialprocess of a procedure supported by the system without being configuredby an additional procedure. In this specification, this procedure willbe referred to as an initialization procedure.

Parameters needed in the initialization procedure may be determinedaccording to functions supported by a corresponding link layer and typesof operating modes possessed by each function. A description will begiven hereinafter of the parameters capable of determining functionsconstituting the link layer and operation modes according to thefunctions.

The above-described drawing illustrates parameters for identifying anencapsulation mode.

When a procedure for encapsulating a packet in a link layer or a higherlayer (e.g., an IP layer) can be configured, indexes are assigned torespective encapsulation modes and a proper field value may be allocatedto each index. The drawing illustrates an embodiment of a field valuemapped to each encapsulation mode. While it is assumed that a 2-bitfield value is assigned in this embodiment, the field value may beexpanded within a range permitted by the system in actualimplementation, when more supportable encapsulation modes are present.

In this embodiment, if a field of information indicating anencapsulation mode is set to ‘00’, the corresponding information mayrepresent that encapsulation in a link layer is bypasses and notperformed. If a field of information indicating an encapsulation mode isset to ‘01’, the corresponding information may represent that data isprocessed by a first encapsulation scheme in the link layer. If a fieldof information indicating an encapsulation mode is set to ‘10’, thecorresponding information may represent that data is processed by asecond encapsulation scheme in the link layer. If a field of informationindicating an encapsulation mode is set to ‘11’, the correspondinginformation may represent that data is processed by a thirdencapsulation scheme in the link layer.

FIG. 26 is a diagram illustrating information for identifying a headercompression mode according to an embodiment of the present invention.

Processing in a link layer may include a function of header compressionof an IP packet. If a few IP header compression schemes are capable ofbeing supported in the link layer, a transmitter may determine whichscheme the transmitter is to use.

Determination of a header compression mode generally accompanies anencapsulation function. Therefore, when the encapsulation mode isdisabled, the header compression mode may also be disabled. Theabove-described drawing illustrates an embodiment of a field valuemapped to each header compression mode. While it is assumed that a 3-bitfield value is assigned in this embodiment, the field value may beexpanded or shortened within a range permitted by the system in actualimplementation according to a supportable header compression mode.

In this embodiment, if a field of information indicating the headercompression mode is set to ‘000’, the corresponding information mayindicate that header compression processing for data is not performed ina link layer. If a field of information indicating the headercompression mode is set to ‘001’, the corresponding information mayindicate that header compression processing for data in the link layeruses an RoHC scheme. If a field of information indicating the headercompression mode is set to ‘010’, the corresponding information mayindicate that header compression processing for data in the link layeruses a second RoHC scheme. If a field of information indicating theheader compression mode is set to ‘011’, the corresponding informationmay indicate that header compression processing for data in the linklayer uses a third RoHC scheme. If a field of information indicating theheader compression mode is set to ‘100’ to ‘111’, the correspondinginformation may indicate that header compressing for data is reserved asa region for identifying a new header compression processing scheme fordata in the link layer.

FIG. 27 is a diagram illustrating information for identifying a packetreconfiguration mode according to an embodiment of the presentinvention.

To apply a header compression scheme to a unidirectional link such as abroadcast system, the broadcast system (transmitter and/or receiver)needs to rapidly acquire context information. The broadcast system maytransmit/receive a packet stream after a header compression procedure inan out-of-band form through reconfiguration of partial compressedpackets and/or extraction of context information. In the presentinvention, a mode for reconfiguring a packet or performing processingsuch as addition of information capable of identifying the structure ofthe packet may be referred to as a packet reconfiguration mode.

The packet reconfiguration mode may use a few schemes and the broadcastsystem may designate a corresponding scheme in an initializationprocedure of a link layer. The above-described drawing illustrates anembodiment of an index and a field value mapped to the packetreconfiguration mode. While it is assumed that a 2-bit field value isassigned in this embodiment, the field value may be expanded orshortened within a range permitted by the system in actualimplementation according to a supportable packet reconfiguration mode.

In this embodiment, if a field of information indicating the packetreconfiguration mode is set to ‘00’, corresponding information mayrepresent that reconfiguration for a packet transmitting data is notperformed in a link layer. If a field of information indicating thepacket reconfiguration mode is set to ‘01’, corresponding informationmay represent that a first reconfiguration scheme is performed for apacket transmitting data in the link layer. If a field of informationindicating the packet reconfiguration mode is set to ‘10’, correspondinginformation may represent that a second reconfiguration scheme isperformed for a packet transmitting data in the link layer. If a fieldof information indicating the packet reconfiguration mode is set to‘11’, corresponding information may represent that a thirdreconfiguration scheme is performed for a packet transmitting data inthe link layer.

FIG. 28 is a diagram illustrating a context transmission mode accordingto an embodiment of the present invention.

A transmission scheme of the above-described context information mayinclude one or more transmission modes. That is, the broadcast systemmay transmit the context information in many ways. In the broadcastsystem, a context transmission mode may be determined according to thesystem and/or a transmission path of a logical physical layer andinformation for identifying the context transmission scheme may besignaled. The above-described drawing illustrates an embodiment of anindex and a field value mapped to the context transmission mode. Whileit is assumed that a 3-bit field value is assigned in this embodiment,the field value may be expanded or shortened within a range permitted bythe system in actual implementation according to a supportable contexttransmission mode.

In this embodiment, if a field of information indicating the contexttransmission mode is set to ‘000’, corresponding field information mayrepresent that context information is transmitted as a firsttransmission mode. If a field of information indicating the contexttransmission mode is set to ‘001’, corresponding information mayrepresent that context information is transmitted as a secondtransmission mode. If a field of information indicating the contexttransmission mode is set to ‘010’, corresponding information mayrepresent that context information is transmitted as a thirdtransmission mode. If a field of information indicating the contexttransmission mode is set to ‘011’, corresponding information mayrepresent that context information is transmitted as a fourthtransmission mode. If a field of information indicating the contexttransmission mode is set to ‘100’, corresponding information mayrepresent that context information is transmitted as a fifthtransmission mode. If a field of information indicating a contexttransmission mode is set to ‘101’ to ‘111’, corresponding informationmay represent that context information is reserved to identify a newtransmission mode.

FIG. 29 is a diagram illustrating initialization information when RoHCis applied by a header compression scheme according to an embodiment ofthe present invention.

While the case in which RoHC is used for header compression has beendescribed by way of example in the present invention, similarinitialization information may be used in the broadcast system even whena header compression scheme of other types is used.

In the broadcast system, transmission of initialization informationsuitable for a corresponding compression scheme according to a headercompression mode may be needed. In this embodiment, an initializationparameter for the case in which a header compression mode is set to RoHCis described. Initialization information for RoHC may be used totransmit information about configuration of an RoHC channel which is alink between a compressor and a decompressor.

One RoHC channel may include one or more context information andinformation commonly applied to all contexts in the RoHC channel may betransmitted/received by being included in the initializationinformation. A path through which related information is transmitted byapplying RoHC may be referred to as an RoHC channel and, generally, theRoHC channel may be mapped to a link. In addition, the RoHC channel maybe generally transmitted through one DP and, in this case, the RoHCchannel may be expressed using information related to the DP.

The initialization information may include link id information, max_cidinformation, large_cids information, num_profiles information, profiles() information, num_IP_stream information, and/or IP_address( )information.

link_id information represents an ID of a link (RoHC channel) to whichcorresponding information is applied. When the link or the RoHC channelis transmitted through one DP, link_id information may be replaced withDP_id.

max_cid information represents a maximum value of a CID. max_cidinformation may be used to inform a decompressor of the maximum value ofthe CID.

large_cids information has a Boolean value and identifies whether ashort CID (0 to 15) is used or an embedded CID (0 to 16383) is used inconfiguring a CID. Therefore, a byte size expressing the CID may also bedetermined.

num_profiles information represents the number of profiles supported inan identified RoHC channel.

profiles( ) information represents a range of a protocolheader-compressed in RoHC. Since a compressor and a decompressor shouldhave the same profile in RoHC to compress and recover a stream, areceiver may acquire a parameter of RoHC used in a transmitter fromprofiles( ) information.

num_IP_stream information represents the number of IP streamstransmitted through a channel (e.g., an RoHC channel).

IP_address information represents an address of an IP stream. IP_addressinformation may represent a destination address of a filtered IP streamwhich is input to an RoHC compressor (transmitter).

FIG. 30 is a diagram illustrating information for identifying link layersignaling path configuration according to an embodiment of the presentinvention.

In the broadcast system, generally, a path through which signalinginformation is delivered is designed not to be changed. However, whenthe system is changed or while replacement between different standardsoccurs, information about configuration of a physical layer in whichlink layer signaling information rather than an IP packet is transmittedneeds to be signaled. In addition, when a mobile receiver moves betweenregions covered by transmitters having different configurations, sincepaths through which link layer signaling information is transmitted maydiffer, the case in which link layer signaling path information shouldbe transmitted may occur. The above-described drawing illustratesinformation for identifying a signaling path which is a path throughwhich the link layer signaling information is transmitted/received.Indexes may be expanded or shortened with respect to the link layersignaling information according to a signaling transmission pathconfigured in a physical layer. Separately from configuration in a linklayer, operation of a corresponding channel may conform to a procedureof the physical layer.

The above-described drawing illustrates an embodiment in whichinformation about signaling path configuration is allocated to a fieldvalue. In this specification, when multiple signaling paths aresupported, indexes may be mapped to signaling paths having greatimportance in order of small values. Signaling paths having priorityprioritized according to an index value may also be identified.

Alternatively, the broadcast system may use all signaling paths havinghigher priority than signaling paths indicated by the information aboutsignaling path configuration. For example, when a signaling pathconfiguration index value is 3, a corresponding field value may be ‘011’indicating that all of a dedicated data path, a specific signalingchannel (FIC), and a specific signaling channel (EAC), priorities ofwhich are 1, 2, and 3, are being used.

Signaling of the above scheme can reduce the amount of data thattransmits signaling information.

FIG. 31 is a diagram illustrating information about signaling pathconfiguration by a bit mapping scheme according to an embodiment of thepresent invention.

The above-described information about signaling path configuration maybe transmitted/received through definition of a bit mapping scheme. Inthis embodiment, allocation of 4 bits to the information about signalingpath configuration is considered and signaling paths corresponding torespective bits b1, b2, b3, and b4 may be mapped. If a bit value of eachposition is 0, this may indicate that a corresponding path is disabledand, if a bit value of each position is 1, this may indicate that acorresponding path is enabled. For example, if a 4-bit signaling pathconfiguration field value is ‘1100’, this may indicate that thebroadcast system is using a dedicated DP and a specific signalingchannel (FIC) in a link layer.

FIG. 32 is a flowchart illustrating a link layer initializationprocedure according to an embodiment of the present invention.

If a receiver is powered on or a mobile receiver enters a transmissionregion of a new transmitter, the receiver may perform an initializationprocedure for all or some system configurations. In this case, aninitialization procedure for a link layer may also be performed. Initialsetup of the link layer in the receiver, using the above-describedinitialization parameters may be performed as illustrated in thedrawing.

The receiver enters an initialization procedure of a link layer(JS32010).

Upon entering the initialization procedure of the link layer, thereceiver selects an encapsulation mode (JS32020). The receiver mayselect the encapsulation mode using the above-described initializationparameters in this procedure.

The receiver determines whether encapsulation is enabled (JS32030). Thereceiver may determine whether encapsulation is enabled using theabove-described initialization parameters in this procedure.

Generally, since a header compression scheme is applied after theencapsulation procedure, if an encapsulation mode is disabled, thereceiver may determine that a header compression mode is disabled(JS32080). In this case, since it is not necessary for the receiver toproceed to the initialization procedure any more, the receiver mayimmediately transmit data to another layer or transition to a dataprocessing procedure.

The receiver selects a header compression mode (JS32040) when theencapsulation mode is enabled. Upon selecting the header compressionmode, the receiver may determine a header compression scheme applied toa packet, using the above-described initialization parameter.

The receiver determines whether header compression is enabled (JS32050).If header compression is disabled, the receiver may immediately transmitdata or transition to a data processing procedure.

If header compression is enabled, the receiver selects a packet streamreconfiguration mode and/or a context transmission mode (JS32060 andJS32070) with respect to a corresponding header compression scheme. Thereceiver may select respective modes using the above-describedinformation in this procedure.

Next, the receiver may transmit data for another processing procedure orperform the data processing procedure.

FIG. 33 is a flowchart illustrating a link layer initializationprocedure according to another embodiment of the present invention.

The receiver enters an initialization procedure of a link layer(JS33010).

The receiver identifies link layer signaling path configuration(JS33020). The receiver may identify a path through which link layersignaling information is transmitted, using the above-describedinformation.

The receiver selects an encapsulation mode (JS33030). The receiver mayselect the encapsulation mode using the above-described initializationparameter.

The receiver determines whether encapsulation is enabled (JS33040). Thereceiver may determine whether encapsulation is enabled, using theabove-described initialization parameter in this procedure.

Generally, since a header compression scheme is applied after theencapsulation procedure, if an encapsulation mode is disabled, thereceiver may determine that a header compression mode is disabled(JS34100). In this case, since it is not necessary for the receiver toproceed to the initialization procedure any more, the receiver mayimmediately transmit data to another layer or transition to a dataprocessing procedure.

The receiver selects a header compression mode (JS33050) when theencapsulation mode is enabled. Upon selecting the header compressionmode, the receiver may determine a header compression scheme applied toa packet, using the above-described initialization parameter.

The receiver determines whether header compression is enabled (JS33060).If header compression is disabled, the receiver may immediately transmitdata or transition to the data processing procedure.

If header compression is enabled, the receiver selects a packet streamreconfiguration mode and/or a context transmission mode (JS33070 andJS32080) with respect to a corresponding header compression scheme. Thereceiver may select respective modes using the above-describedinformation in this procedure.

The receiver performs header compression initialization (JS33090). Thereceiver may use the above-described information in a procedure ofperforming header compression initialization. Next, the receiver maytransmit data for another processing procedure or perform the dataprocessing procedure.

FIG. 34 is a diagram illustrating a signaling format for transmitting aninitialization parameter according to an embodiment of the presentinvention.

To actually transmit the above-described initialization parameter to areceiver, the broadcast system may transmit/receive correspondinginformation in the form of a descriptor. When multiple links operated ina link layer configured in the system are present, link_id informationcapable of identifying the respective links may be assigned anddifferent parameters may be applied according to link_id information.For example, if a type of data transmitted to the link layer is an IPstream, when an IP address is not changed in the corresponding IPstream, configuration information may designate n IP address transmittedby a higher layer.

The link layer initialization descriptor for transmitting theinitialization parameter according to an embodiment of the presentinvention may include descriptor_tag information, descriptor_lengthinformation, num_link information, link_id information,encapsulation_mode information, header_compression_mode information,packet_reconfiguration_mode information, context_transmission_modeinformation, max_cid information, large_cids information, num_profilesinformation, and/or profiles( ) information. A description of the aboveinformation is replaced with a description of the above-describedinformation having a similar or identical name.

FIG. 35 is a diagram illustrating a signaling format for transmitting aninitialization parameter according to another embodiment of the presentinvention.

The drawing illustrates a descriptor of another form to actuallytransmit the above-described initialization parameter to a receiver. Inthis embodiment, the above-described initial configuration informationof header compression is excluded. When an additional header compressioninitialization procedure is performed in data processing of each linklayer or an additional header compression parameter is given to a packetof each link layer, the descriptor configured in the same form as inthis embodiment may be transmitted and received.

The link layer initialization descriptor for transmitting theinitialization parameter according to another embodiment of the presentinvention may include descriptor_tag information, descriptor_lengthinformation, num_link information, link_id information,encapsulation_mode information, header_compression_mode information,packet_reconfiguration_mode information, and/orcontext_transmission_mode information. A description of the aboveinformation is replaced with a description of the above-describedinformation having a similar or identical name.

FIG. 36 is a diagram illustrating a signaling format for transmitting aninitialization parameter according to another embodiment of the presentinvention.

The drawing illustrates a descriptor of another form to actuallytransmit the above-described initialization parameter to a receiver. Inthis embodiment, a descriptor for transmitting the initializationparameter includes configuration information about a signalingtransmission path without including initial configuration information ofheader compression.

The configuration parameter about the signaling transmission path mayuse a 4-bit mapping scheme as described above. When a broadcast system(or transmitter or a receiver) for processing a broadcast signal ischanged, a link layer signaling transmission scheme or the contents oflink layer signaling may differ. In this case, if the initializationparameter is transmitted in the same form as in this embodiment, theinitialization parameter may be used even in the case of change of linklayer signaling.

The link layer initialization descriptor for transmitting theinitialization parameter according to another embodiment of the presentinvention may include descriptor_tag information, descriptor_lengthinformation, num_link information, signaling_path configurationinformation, dedicated_DP_id information, link_id information,encapsulation_mode information, header_compression_mode information,packet_reconfiguration_mode information, and/orcontext_transmission_mode information.

When the link layer signaling information is transmitted through adedicated DP, dedicated_DP_id information is information identifying thecorresponding DP. When the dedicated DP is determined as a path fortransmitting the signaling information in signaling path configuration,DP_id may be designated to include DP_id information in the descriptorfor transmitting the initialization parameter.

A description of the above information contained in the descriptor isreplaced with a description of the above-described information having asimilar or identical name.

FIG. 37 is a diagram illustrating a receiver according to an embodimentof the present invention.

The receiver according to an embodiment of the present invention mayinclude a tuner JS21010, an ADC JS21020, a demodulator JS21030, achannel synchronizer & equalizer JS21040, a channel decoder JS21050, anL1 signaling parser JS21060, a signaling controller JS21070, a basebandcontroller JS21080, a link layer interface JS21090, an L2 signalingparser JS21100, packet header recovery JS21110, an IP packet filterJS21120, a common protocol stack processor JS21130, an SSC processingbuffer and parser JS21140, a service map database (DB) JS21150, aservice guide (SG) processor JS21160, a SG DB JS21170, an AV servicecontroller JS21180, a demultiplexer JS21190, a video decoder JS21200, avideo renderer JS21210, an audio decoder JS21220, an audio rendererJS21230, a network switch JS21240, an IP packet filter JS21250, a TCP/IPstack processor JS21260, a data service controller JS21270, and/or asystem processor JS21280.

The tuner JS21010 receives a broadcast signal.

When a broadcast signal is an analog signal, the ADC JS21020 convertsthe broadcast signal to a digital signal.

The demodulator JS21030 demodulates the broadcast signal.

The channel synchronizer & equalizer JS21040 performs channelsynchronization and/or equalization.

The channel decoder JS21050 decodes a channel in the broadcast signal.

The L1 signaling parser JS21060 parses L1 signaling information from thebroadcast signal. The L1 signaling information may correspond tophysical layer signaling information. The L1 signaling information mayinclude a transmission parameter.

The signaling controller JS21070 processes the signaling information orthe broadcast receiver transmits the signaling information to anapparatus that requires the corresponding signaling information.

The baseband controller JS21080 controls processing of the broadcastsignal in a baseband. The baseband controller JS21080 may performprocessing in the physical layer on the broadcast signal using the L1signaling information. When a connection relation between the basebandcontroller JS21080 and other apparatuses is not indicated, the basebandcontroller JS21080 may transmit the processed broadcast signal orbroadcast data to another apparatus in the receiver.

The link layer interface JS21090 accesses the link layer packet andacquires the link layer packet.

The L2 signaling parser JS21100 parses L2 signaling information. The L2signaling information may correspond to information included in theaforementioned link layer signaling packet.

When header compression is applied to a packet of a higher layer (e.g.,an IP packet) than a link layer, the packet header recovery JS21110performs header decompression on the packet. Here, the packet headerrecovery JS21110 may restore a header of the packet of the higher layerusing information for identification of whether the aforementionedheader compression is applied.

The IP packet filter JS21120 filters the IP packet transmitted to aspecific IP address and/or UDP number. The IP packet transmitted to thespecific IP address and/or UDP number may include signaling informationtransmitted through the aforementioned dedicated channel. The IP packettransmitted to the specific IP address and/or UDP number may include theaforementioned FIC, FIT, EAT, and/or emergency alert message (EAM).

The common protocol stack processor JS21130 processes data according toa protocol of each layer. For example, the common protocol stackprocessor JS21130 decodes or parses the corresponding IP packetaccording to a protocol of an IP layer and/or a higher layer than the IPlayer.

The SSC processing buffer and parser JS21140 stores or parses signalinginformation transmitted to a service signaling channel (SSC). Thespecific IP packet may be designated as an SSC and the SSC may includeinformation for acquisition of a service, attribute information includedin the service, DVB-SI information, and/or PSI/PSIP information.

The service map DB JS21150 stores a service map table. The service maptable includes attribute information about a broadcast service. Theservice map table may be included in the SSC and transmitted.

The SG processor JS21160 parses or decodes a service guide.

The SG DB JS21170 stores the service guide.

The AV service controller JS21180 performs overall control foracquisition of broadcast AV data.

The demultiplexer JS21190 divides broadcast data into video data andaudio data.

The video decoder JS21200 decodes video data.

The video renderer JS21210 generates video provided to a user using thedecoded video data.

The audio decoder JS21220 decodes audio data.

The audio renderer JS21230 generates audio provided to the user usingthe decoded audio data.

The network switch JS21240 controls an interface with other networksexcept for a broadcast network. For example, the network switch JS21240may access an IP network and may directly receive an IP packet.

The IP packet filter JS21250 filters an IP packet having a specific IPaddress and/or a UDP number.

TCP/IP stack processor JS21260 decapsulates an IP packet according to aprotocol of TCP/IP.

The data service controller JS21270 controls processing of a dataservice.

The system processor JS21280 performs overall control on the receiver.

FIG. 38 is a diagram illustrating a broadcast system according to anembodiment of the present invention.

The broadcast system according to an embodiment of the present inventionmay include a broadcast transmitter J38010 and/or a broadcast receiverJ38110.

The broadcast transmitter J38010 includes an IP packet generator J38020,a link layer packet generator J38030, a broadcast signal generatorJ38040, and/or a signaling encoder J38050.

The IP packet generator J38020 generates and processes IP packets. Forexample, the IP packet generator J38020 generates first IP packetsincluding broadcast data for a broadcast service and a second IP packetincluding service acquisition information including informationnecessary for fast acquisition of the broadcast service.

The link layer packet generator J38030 generates and processes linklayer packets. For example, the link layer packet generator J38030 maygenerate first link layer packets including the first IP packets.

The IP packet generator and the link layer packet generator may beimplemented through one device.

The broadcast signal generator J38040 generates a broadcast signal fortransmitting broadcast data through a physical layer. The broadcastsignal generator J38040 generates the broadcast signal including thefirst link layer packets and the second IP packet.

The signaling encoder J38050 generates signaling information. Thesignaling encoder J38050 may generate all or some of the signalinginformation. The signaling encoder J38050 may transmit signalinginformation that is necessary to be transmitted through an IP layer tothe IP packet generator and transmit signaling information that isnecessary to be transmitted through a link layer to the link layerpacket generator.

The broadcast receiver J38110 may include a receiving unit J38120, alink layer processing unit J38130, an IP layer processing unit J38140, asignaling processing unit J38150, and/or a processor J38160.

The receiving unit J38120 receives the broadcast signal. The receivingunit J38120 may receive the broadcast signal including the first linklayer packets and the second IP packet. In this case, the second IPpacket may include service acquisition information including informationnecessary to rapidly acquire a broadcast service. The receiving unitJ38120 may include a tuner and/or a network interface. The networkinterface may receive a broadcast signal of each type according to aproperty of a broadcast network. For example, the network interface mayreceive a broadcast signal transmitted over an IP network.

The link layer processing unit J38130 processes data in a link layer.The link layer processing unit J38130 may obtain the first IP packetsincluding broadcast data for a broadcast service by decapsulating thefirst link layer packets.

The IP layer processing unit J38140 processes data in an IP layer. TheIP layer processing unit J38140 may acquire the broadcast data bydecapsulating the first IP packets, using the service acquisitioninformation.

The signaling processing unit J38150 parses signaling information. Thesignaling processing unit J38150 may parse signaling informationtransmitted through a physical layer, a link layer, and/or an IP layer.The signaling processing unit J38150 may acquire signaling informationand transmit the signaling information to a device and/or a module ofthe receiver requiring this signaling information. The signalingprocessing unit J38150 may acquire the service acquisition informationby decapsulating the second IP packet.

The processor J38160 processes broadcast data. The processor J38160 maydecode audio and/or video from the broadcast data. The processor J38160may include the above-described link layer processing unit J38130, theIP layer processing unit J38140, and/or the signaling processing unitJ38150. The processor J38160 reproduces and processes broadcast contentusing the broadcast data.

Modules, processing units, devices, or units may be processors forperforming consecutive execution procedures stored in a memory (or astorage unit). Steps described in the above-described embodiments may beperformed by hardware/processors. The modules/blocks/units described inthe above-described embodiments may operate as hardware/processors. Inaddition, methods proposed in the present invention may be executed bycode. This code may be written in a processor-readable storage mediumand, therefore, read by a processor provided by an apparatus.

The methods according to the present invention may be implemented asprogram instructions that can be executed by various computer means andwritten in a computer-readable recording medium.

The computer-readable recording medium may include a programinstruction, a data file, a data structure, etc. alone or incombination. The program instruction written in the medium may bedesigned or configured especially for the present invention or known tothose skilled in computer software. Examples of the computer-readablerecording medium include magnetic media such as a hard disk, a floppydisk, and a magnetic tape, optical media such as a CD-ROM and a DVD,magneto-optical media such as a floptical disk, and a hardware deviceconfigured especially to store and execute a program instruction, suchas a ROM, a RAM, and a flash memory. Examples of the program instructioninclude a high-level language code executable by a computer using aninterpreter as well as a machine language code generated by a compiler.The hardware device may be configured to operate as one or more softwaremodules to implement an operation of the present invention or viceversa.

Although the present invention has been described with reference to thepreferred embodiments, it will be apparent to those skilled in the artthat various improvements, modifications, replacements, and additionscan be made without departing from the scope and spirit of theinvention. Accordingly, the scope of the present invention should not belimited to the description of the embodiment, but defined by theaccompanying claims and equivalents thereof.

Various embodiments have been described in the best mode for carryingout the invention.

The present invention is applicable to all broadcast industries.

What is claimed is:
 1. A digital broadcast receiver for processing abroadcast signal, the digital broadcast receiver comprising: a tunerconfigured to receive the broadcast signal including Physical LayerPipes (PLPs), wherein the PLPs carry link layer packets; and acontroller coupled to the tuner, wherein the controller is configuredto: decode a specific PLP, acquire signaling information for headercompression, wherein the signaling information for header compressionincludes a PLP identifier for the signaling information for headercompression, profile information for representing a range of multipleprotocols used to compress at least one stream, and a maximum value of acontext identifier, decode another PLP to receive the at least onecompressed stream based on the signaling information for headercompression, and decompress the at least one compressed stream.
 2. Thedigital broadcast receiver according to claim 1, wherein the link layerpackets include one or more Internet Protocol (IP) packets carryingservice acquisition information, and wherein the service acquisitioninformation includes information necessary for fast acquisition of abroadcast service.
 3. The digital broadcast receiver according to claim2, wherein the link layer packets further include mapping informationbetween IP addresses of the one or more IP packets and the PLPs.
 4. Amethod for receiving at least one broadcast signal in a digitalbroadcast receiver, the method comprising: receiving the at least onebroadcast signal including Physical Layer Pipes (PLPs) in a tuner,wherein the PLPs carry link layer packets; decoding a specific PLP;acquiring signaling information for header compression, wherein thesignaling information for header compression includes a PLP identifierfor the signaling information for header compression, profileinformation for representing a range of multiple protocols used tocompress at least one stream, and a maximum value of a contextidentifier; decoding another PLP to receive the at least one compressedstream based on the signaling information for header compression; anddecompressing the at least one compressed stream.
 5. The methodaccording to claim 4, wherein the link layer packets include one or moreInternet Protocol (IP) packets carrying service acquisition information,and wherein the service acquisition information includes informationnecessary for fast acquisition of a broadcast service.
 6. The methodaccording to claim 5, wherein the link layer packets further includemapping information between IP addresses of the one or more of IPpackets and the PLPs.
 7. A method for transmitting a broadcast signal ina digital broadcast transmitter, the method comprising: generating acompression information table for a header compression for at least oneInternet Protocol (IP) packet; encapsulating the at least one IP packetinto at least one link layer packet, wherein the compression informationtable for the header compression for the at least one IP packet includesa Physical Layer Pipe (PLP) identifier for identifying at least one PLP,wherein the compression information table for the header compression forthe at least one IP packet further includes a maximum value of a contextidentifier to be used for the at least one PLP, and wherein thecompression information table for the header compression for the atleast one IP packet further includes profile information forrepresenting a range of multiple protocols used to compress an IPstream; and transmitting the broadcast signal including the at least onePLP that carries the at least one link layer packet.
 8. The method ofclaim 7, wherein a number of bits for the PLP identifier is smaller thana number of bits for the maximum value of the context identifier, and anumber of bits for the profile information corresponds to eight bits. 9.A digital broadcast transmitter for transmitting a broadcast signal, thedigital broadcast transmitter comprising: a processor configured to:generate a compression information table for a header compression for atleast one Internet Protocol (IP) packet, and encapsulate the at leastone IP packet into at least one link layer packet, wherein thecompression information table for the header compression for the atleast one IP packet includes a Physical Layer Pipe (PLP) identifier foridentifying at least one PLP, wherein the compression information tablefor the header compression for the at least one IP packet furtherincludes a maximum value of a context identifier to be used for the atleast one PLP, and wherein the compression information table for theheader compression for the at least one IP packet further includesprofile information for representing a range of multiple protocols usedto compress an IP stream; and a transmitter configured to transmit thebroadcast signal including the at least one PLP that carries the atleast one link layer packet.
 10. The digital broadcast transmitter ofclaim 9, wherein a number of bits for the PLP identifier is smaller thana number of bits for the maximum value of the context identifier, and anumber of bits for the profile information corresponds to eight bits.